Airsoft can be an expensive hobby.  Guns from notable manufacturers such as Tokyo Marui and Classic Army can run you upwards of $250 if you buy them retail, making buying online an attractive option.  Puchasing items unseen or untested is a risky business, however, and airsoft weapons high rate of failure can magnify the risk exponentially.  This guide is designed to help you pick and choose what to look for when you are puchasing airsoft on ebay.

First a bit on Airsoft.  Airsoft guns use compressed air to project a 6mm plastic BB out of a barrel and towards a target.  The method the air used is compressed may vary, but the same concept applies to all.  Airsoft guns are usually (if they are legal) marked with an orange tip and typically resemble actual fire arms.  They can range from speeds of 100 FPS (feet per second) all the way up to 600 FPS (on modified guns).  Extra distance is achieved on many guns by using a system called Hop-up.  Hop-up puts a backspin on the BB, causing it to rise.  On models with adjustable hop up, this same system can be used to make a BB fire level at a distance instead of curving downwards due to gravity.  BBs themselves vary in weight starting at .12 grams all the way up to .38 (maybe even higher)grams.  The weight of the BB used should be determined by the power of the gun.  Heavier BBs in a powerful gun will increase accuracy and decrease problems caused by outside sources such as wind.  Now, on to how to find one of these guns.

Search Words:  A general search of the word airsoft will yield hundreds of results.  It helps to narrow the search down by researching what you want before you go looking to buy.  What kind of gun do you want?  Is there a brand you like?  What propulsion system do you want?  Are metal parts important to you? Below I have outlined a few words that will help you narrow your search.

Gun Types:  Below are some common gun models. Using the general type of gun in the search (assault rifle, smg, sniper rifle, etc) will usually come up with some, if not all, of the specific gun types listed.  When picking a type, think hard about the terrain you play in and the tactics your team uses.  A sniper will be rendered useless if you play in a confined space, while a pistol won't hit anything over 100 feet (there are exceptions, of course).  Weight of your weapon should also be considered, since it will test your endurance and reaction time.  A 3-4lb SMG usually draws quicker than a 6lb assault rifle and you can carry it longer without discomfort.

• Assault Rifles: M4, M14, M15, M16, M733, AK47, G3, G36, FaMAS, Thompson M1A1, Sig 552, AUG
  
• SMG:  MP5, UZI, Mac10, AK74, UMP, M5, P90
  
• Sniper Rifles: PSG-1, Type 96, VSR-10, M700, Dragunov, M24
• Machine Guns: M60, M240G, M249
• Pistols:  Desert Eagle, M9, Glock, G18, Raging Bull, Python, 1911, etc. (it is impractical to list all the different pistiol types, given that just about every pistol that exists has been made into an airsoft gun)
• Shotgun: (if you are looking for shotguns, typing shotgun is usually enough.  You may want to add the word "multi-shot" if that is something you desire out of your shotgun.)

Brands: Here are some of the brands that are generally considered to be high quality.  You will notice two names in particular, Tokyo Marui (TM) and Classic Army (CA) coming up quite a bit.  That is because these two brands are the standard by which all others are judged.  Many sellers will use these tags to get people to look at their product.  Many guns are "clones" (meaning exact or near exact copies) of these brands of guns which means upgrades and magazines for TM or CA will (usually) work with them.  This is also something to consider when buying a gun for serious, competitive use.  Use these brands as search words to help narrow down price and quality levels.  *Note: Many guns considered mid range offer the same quality performance as high range guns.  Often the differences are merely cosmetic, usually involving how much of the gun is metal vs how much is plastic, but a performance issue can usually be adjusted by buying upgrades and still offering a lower price.  My advice is pick a budget and stick to it.  Do not overspend on a high end gun and be left with no money for upgrades, BBs, tactical gear, plus be stuck with an underpowered gun (I'm looking at you, Tokyo Marui). 

• High End Brands, for pros and serious competitors/collectors, typically contain more metal parts than lower brands, usually $250+:  Tokyo Marui, Classic Army,  ICS,  Star, G&G, G&P
  
• Mid-High, for pros on a budget, entry level competitiors $175-$250:  Echo1, CA Sportline,  DPMS*
• Mid, good for first time buyers, casual competitors, $100-$175: Jing Gong*, UTG, AGM, Cyma*, ARMY China*, Tippmann
  
• Low, nearing almost toy like quality. fun for messin around:  Dboys*, Firepower, Crossman, Double Eagle

* These brands make a wide variety of guns at different levels of quality.  DO NOT BUY ON BRAND NAME ALONE.  Do some research on the gun, it will save you a lot of grief.

Note: These are not all the brands of Airsoft, just some of the more common ones.  Many firearm manufacturers sell airsoft guns under their own names. For example, Remington.

Propulsion system:  How the gun fires BBs affects the gun perhaps more than any other factor.  Spring guns are cheap to use and (usually) buy, but they lack full automatic firing of an Electric or Gas type.  Here are some pros and cons (plus the word to use when searching)

Spring search word(s) Spring, Springer
Pros

• Cheap initial cost and maitenance
• Cheap to use
• Easier to upgrade
• High FPS for less $$
• Reliable, less parts= less broken parts
• Less subject to environemtal conditions then Electric, Gas
  

Cons

• No full auto
• No semi auto
• See first two reasons

Electric search word(s) Electric, AEG, Battery Powered
Pros

• Fast rate of fire
• Rechargable battery
• Common, easy to find parts, upgrades
• Safe transport/storage

Cons

• Battery life can shorten a day
  
• Typically lower FPS out of the box
• Durability, its not if the gun will wear out, its when.

Gas search word(s) Butane, Green Gas, Propane, Red Gas, CO2, Carbon Dioxide (like whos gonna type that) Note: Gas powered airsoft guns use three major gasses, Butane, Propane, and CO2.  Know which the gun in question uses and how available it is in your area before purchasing.
Pros

• High rate of fire AND FPS achievable on nearly any gas gun
• Quicker to refill gas than to charge electric
• Compact guns like pistols can achieve amazing power

Cons

• High cost to operate.  The price of gas these days...
• Can be dangerous if left in a heated situation a.k.a. your car.  Heat plus Butane = BOOOOM.  CO2 is not flammable, however.  Just expenisve.
• Look, you can operate a gas gun cheaply(err, er) if you buy an adapter that will work on a propane tank.  The key if doing this is you must lube the gun yourself.  This does not apply to CO2 guns, which are just silly.  If you are buying co2, buy a paintball gun. Personal opinion.

Now, lets apply the topics just went over to an Ebay search.  Let's try searching for a Tokyo Marui AEG M4 Assault Rifle.  Here is the search results *Note: I dont know if this link worked, but if it didnt, please try typing the previously mentioned search words into the designated area.  Notice how you get results for a JG M4?  That is a Jing Gong rifle.  I told you Tokyo Marui would come up a lot.  You may find it hard to find a genuine Marui on ebay, so use caution.  Read the entire description and possibly contact the seller if you cannot absolutely be sure of the brand.  Remember the retail price difference between Jing Gong and Tokyo Marui can be over $100 and you dont want to get ripped off.  Use the same caustion when searching for Classic Army weapons, as the Sportline models are different then the genuine article.  Lets try a lower range gun.  How about UTG Type 96 Sniper. Here is what I got. *Note: See above note.  You may want to resource other websites in your research in order to find a fair retail price.  Many sellers are SEVERELY exaggerating price on Ebay.  I cannot give you a link, but if you Google Wisconsin Airsoft Wars you may find a helpful site for researching,  maybe buying (if Ebay does not have what you are looking for of course ;)

I hope this guide gives you a basic understanding on what kinds of Airsoft guns there are and what to look for on ebay.  My greatest piece of advice I can give you here is buyer be warned.  Find out as much as you can about a gun from as many places you can before buying.  DO NOT TRUST SELLERS!  Too many exaggerate gun details, and I would hate to see you turned off of a growing sport before you get a chance to experience it properly.  Also remember this: SAFETY FIRST!  Do not operate ANY airsoft gun without EYE PROTECTION!  Do not shoot at something you dont want broken or hurt.  Treat Airsoft guns as if they were actual fire arms. Only shoot at others in a controlled, safe setting with people who are fully protected and are agreeing to get shot at.  Check with local authorities before using any gun inside city limits, as laws vary from city to city, state to state.  Happy hunting.