I can not count how many people try, and do actually make money on eBay from excessive shipping costs.  I would like to start out with a short story of a person who was selling a video game console here on eBay.  Here's how it went:

I saw a Playstation 3 (auction-stlye listing) that was going to end in about 1 day.  The console was at $100.00 (which was very cheap), and there were no bids on it, so curious as I was that there were no bids, i decided to chekc it out.  Then i realized why there were no bids on the item.  The shipping cost was ridiculous.  A whopping $480.00!!  Now, i wasn't going to buy the product anyways, but i decided to email the seller and ask him/her why the shipping cost was so high.  Here was his answer; "Well, a couple reasons.  My first is because I may have to ship the item very far.  I am also not sure were i have to ship the item until after the auction is won.  This shipping cost also includes delivery confirmation from USPS.  I will be shipping USPS First Class Mail.  Thanks!".  We all know that is way too high of a shipping price, and that this person was simply trying to scam the buyer into buying the item.  I mean...you could ship that thing Global Express Mail all the way to Australia.  And the shipping cost would still be lower (believe me, I checked).  After getting all the answers, i decided to report him just before the item ended, and that's the last I saw of it.

Now this isn't to say, if you accidently went over the actual shipping amount by a couple dollars, heck, even $10/$15 if the item was huge, you're in big trouble.  I realize that sometimes it's hard to calculate the shipping amount.  But $480.00.  I mean c'mon.  And that's just an extremely exagerated shipping cost example.  There are other people listing items and making the shipping cost $40.00 when it is actually only $10.00 to ship the item.  Also, for the people who don't know, it's against eBay's rules to charge excessive shipping, so you could be reported for something like this.  Also, i would not try and estimate the shipping charges (unless you are very good at it) because that could cause problems for you and/or the seller. 

Why Do People Do This?

First of all, they save money because eBay does not "see", or calculate the shipping cost when giving a final value fee.  Second, sellers (usually always the reason) may do this to hide the true cost of the item from buyers looking to purchase that item.  Unfortunately, some people do fall for this trick.

Ways To Avoid Charging Your Buyer's Excessive Shipping Charges:

-There is the "Shipping Wizard" that can estimate the approximate amount (not as good)

-Go to the shipper's website (USPS/UPS, etc.).  Here, you can calculate the shipment more in depth.  They ask for the weight, size, and more.  Use the appropriate scale for what you are selling and weigh the item at your house, and use a tape measurer to see what size the box will be.  Then type the calculations into the website to get a more exact shipping cost.

-If none of the above work, you can try using flat rate boxes from USPS (check out my other guide "Save on Shipping with USPS Flat Rate Boxes and Envelopes")

• Just as a side note; Shipping AND Handling are not the same thing.  You may charge the buyer handling fees (as long as they are not excessive) for packaging materials you may have used to protect item from damage. 

These are probably the best ways to avoid excessive shipping costs.  Some people check their package after they recieved their delivery to see the cost of shipping and whether it was accurate or not.  Personally I try to get 5's in all my DSR's, that's why i try and ship USPS Fat Rate every chance i can get, that way there are no questions asked about shipping charges.     

Here's the link if you'd like to read more: http://pages.ebay.com/help/policies/listing-shipping.html

Hopefully this guide was helpful to you.  If it was not tell me why and i will do my best to fix it.  If it was helpful, please rate it with a "yes" vote.