In regards to buying a car on Ebay. I personally haven't, but I know 2 people that have. The first guy is a old friend from university. He and his brother (as a summer hobby - they are both high-school teachers) fix up older vintage collectable cars. On 2 separate occassions, they bought mid-60s vintage Ford Mustangs on ebay, and drove 14 hours from Toronto, Ontario to somewhere in the US to pick-up the cars (I assume that they paid duties/taxes at the border when returning). Both trips were successful and in the end they sold the cars here for a $4000.00 profit (each car). Not bad...
The other guy I know that bought a car on ebay was actually the guy I bought my Jeep from. He purchased a 2003 Corvette from ebay and drove down with his friend to Pittsburg to pick it up. In the end he said that the same car/year/mileage here would have cost him an additional $10,000 if he had bought the car locally.
I think purchasing cars on Ebay still seems like a radical thing to do, but in time I think you will see a lot more acceptance.....just my opinion.