If you're searching for DVDs of the various Star Trek series, eBay is an excellent way to avoid the high costs of places like Amazon.com and retail stores.  For example, the North American release of Seasons 1-7 (the whole series) of Star Trek: The Next Generation goes for $450 at Best Buy and $315 at Amazon.com.  But it's possible to get the series on eBay for $220 (See my guide How to get a good price on Star Trek DVDs).

However, circumspect buyers will notices that well over half the listings for Star Trek DVDs on eBay aren't offering the same goods that one can find on Amazon.com or in retail stores.  Instead, they're selling cheaper, lower-quality Asian imports. 

What's wrong with these imports?

1) Low quality packaging.  The import versions are packaged in thin, plastic cases that are prone to tearing and cracking.  In addition, the DVDs themselves are stored in cheap plastic and synthetic cases that scratch them.

2) Low quality content.  The imports have VHS-equivalent picture quality and in many cases, the last several minutes of the episode are cut off.

3) Low resale value.  Selling used authentic versions on eBay will guarantee an ~75% recoup of the price you paid for a new version.  Used imports do not sell well on eBay.  You will not be able to make back more than 25% of what you paid.

Clearly, it's better to purchase authentic Region 1 US releases rather than imports.  So how can you tell the difference between the two?

1) It says "Asian import".  In many cases, sellers are honest.  The item description (maybe in small print, maybe clearly) will state "import".  Some sellers disguise this a bit, so if you see "international edition" or (my personal favorite) "Asia collector's edition", you can be certain it's an import version.

2) Different box (possibly with foreign characters). Most sellers will try to hide the fact that they're selling imports.  Some will even outright lie and say "US version" or more often "Region 1 content".  But you can often tell from the pictures.  Remember, Paramount only released ONE version of each series in the United States.  So if the box you see looks different than the one shown on Amazon.com or in retail stores, it MUST be an import.  Specifically, if you look closely, you may see foreign characters on the box.  Others are plain and are totally in English yet clearly different than the official releases.  This is a sure sign that they're import versions.

3) Extremely high shipping costs.  This is an obvious one, but you might not look for it specifically.  Asian imports must be shipped from Asia, so they will cost significantly more to ship than domestically released items.  An average shipping cost for an Asian import is $50.  If shipping costs are more than ~$15, it's probably an import.

4) Emphasis on "English audio".  Sellers will say things like "Original English", "Not overdubbed", and "original actors' voices".  Or it will say, "Subtitle: Enlgish / Other language / Off".  This emphasis that the DVDs are in English is a giveaway that they're imported versions.

5) Incorrect series title.  Bizzarely, I've seen Star Trek: Enterprise listed as Star Trek: Voyager in the auction, yet the four seasons of Enterprise are clearly being sold.  Another odd occurance is something like "Star Trek III: Voyager" (it says this on the boxes too).  These are clearly not US retail versions.

6) Multiple listings.  Often, the exact same set will appear five or ten times in a row.  Those who want to make money by selling authentic US goods space out their listings better.  A glut of listings for the same item is a giveaway about its origin.

7) No PayPal.  Often, sellers of Asian imports who disguise their product by using a different picture or claiming that it's a US release will refuse to accept PayPal because PayPal offers buyer protection, making it more difficult for them to perpitrate fraud.  It's always best to use PayPal as a method of payment.  If not, only use a credit card, ACH transfer, or money order, as these can be traced.  Requests for payment outside of PayPal or these established methods is a giveaway regarding fraud.

8) New user.  Often, users are banned for selling Asian imports but passing them off as US versions.  They tend to resurface under a new user name before being banned again, so be suspicious of newly registered users.

You should be able to spot imports using this guide.  Be sure to buy authentic Region 1 US versions.  The quality product you receive is worth the extra money.