Douglas,
I am not an eBay power seller, or even very active compared to many, but I almost always have things listed. I would like to assume that my experiences are not much different than many others. So, that being said:
1) It is extremely easy for a buyer to CANCEL a bid.
2) It is extremely easy for a buyer to CANCEL a transaction after the auction is closed.
3) It is extremely easy for a buyer to simply NOT PAY (of course they don't get the car, if it indeed exists in the first place.)
4) On nearly everything I've listed for more than $100.00, I consistently get offers to buy outside of the eBay process at a lower price.
5) For 95% of the items I sell, there is no bidding until the last few minutes of the auction. If there is, it is simply ONE bid; the rest happen in the last few seconds.
Thus, I am not sure I'd place much stock or truth into eBay auction prices as a metric of anything. What you see as a lurker doesn't mean the deal actually happened and doesn't necessarily reflect the real price if it did. As an overall measure of the economy's impact on collector cars in general, an analysis of the latest B-J in Phoenix might be useful.
If you want to witness something quite funny, high-end pianos (full size grands, Steinways, Yamaha, etc) are consistently listed on eBay but I don't believe ANY of them actual sell at auction. The storefronts--some well known piano brokers, simply use the eBay auction price as a storefront to drive traffic to their website and as a means of advertising their services and stock. I've seen some of the same pianos showing up for well over a year in many, many auctions from the same sellers. People then surf to the eBay store, or to the owner's website, etc. and a deal is made there (without the eBay fees, might I add--just the listing fee).