Russ,
Well, not much of a start. The unfortunate fact is there are a lot of con artists on eBay. I feel the reason eBay put the buyer and seller guarantees in place was it would be cheaper to just pay those who played by the rules and were cheated, than try and police the creeps.
I did have someone try and cheat me some time ago. A bait and switch. It wound up with eBay refunding the amount from the sellers account and I kept the item as well.
I have always done well on eBay, but I've used it for quite a while and have pretty good radar for nonsense. The first thing is: don't get involved in a transaction for that kind of money with a seller having no feedback score. If they won't answer a question, pass them by and go to the next. There are legit folks out there. It's just a pain to wade through the bad to get to the good.
I fully understand your feeling about it. eBay is not the only place where you can get a scanner. With a bit of searching, I'm guessing you can find one someplace where it's just a buy and sell transaction. It may not be any more expensive than eBay anyway. The thing eBay does is give you a guideline. By looking at the completed transactions, you can get a feeling for what things are selling for.