... Ebay literally gives you a place to specify shipping costs. IF the cost is wrong you can either request a new quote or the seller eats it and ships anyways. ...
I remember bidding on some very heavy items a couple of years ago (vintage items, just not computers; Jari Monarch sickle mowers) where the seller had estimated $200 shipping. I won the auction at $205 or somesuch, making the total $405 or thereabouts. The shipping alone ended up being over $350, but,
a deal's a deal. I felt bad for the guy, but he was totally professional and just simply admitted that he had vastly underestimated the shipping cost, and he ate that cost. I got my two Jari Monarchs (disassembled and crated, shipped by Fedex Freight, with excellent packaging) about three weeks later. The one 36" sickle bar alone was worth the $405.....
Had he even suggested that I should pick up the cost overage that was his fault I would have had him cancel the bid, and he could have re-listed with a better shipping estimate. Never ever would I have wired extra money for his error; that's bad business. Even though I really did feel bad for the guy, as he just barely made up his shipping cost, much less the cost of packaging and his time.
While I won't be as brusque as NeXT, this is an essential eBay lesson:
never ever pay
anything beyond what the seller charges through eBay. Period.