Before eBay I used a site called uBid. They used to extend the auction end time by 60 seconds whenever someone bit to allow time for a counter-offer. They said it was the equivalent of a real auction's "Going for $x... Going... Going... Gone!" which made sense to me. In my opinion eBay should do the same.
That said, eBay does allow you to put in the maximum you're willing to pay, so if you're honest about that about then snipers shouldn't bother you.
That might work to the sellers advantage, but in the long run its just going to elevate prices. The best deals I've gotten on Ebay (like the Quicksilver I'm typing this on) have been relatively uncontested.
BTW - On the Mac, it was listed as non-functional so I thought I'd only get a case out of it. When I got it all I had to do was reseat the CPU card, add memory and a hard drive. The power supply, motherboard, CPU all in perfect working order - $19.95.
The problem with Amiga hardware is its too sought after and the prices get stupid. On Amiga hardware, I'd rather buy directly from the last owner.