I shop ebay 2 ways.........the first is I look for specific items. By doing that, I KNOW what I'm looking for and what the MSRP is. Usually I'm looking for out of production items, and I'll sometimes spend a little extra to get the item. The second is if I just see something that looks interesting. On that stuff, I simply decide what it's worth to me......which may be pretty cheap and place a bid and don't look back. If I get it , great, if I don't, oh well.
I have had only one BAD transaction, where the seller simply disappeared.....but even on that one, I got a call from a detective months later, and they were returning money from the guy. I've had a few "oops, sent the wrong item" problems, but those have usually resulted in an even better deal, either with getting the correct item sent AND keeping the wrong item, or getting the correct item and a refund.. I haven't had any more problems ordering off ebay than I've had ordering online dealers.