I bought my 2000 Audi A6 4.2 off eBay. I am in Maryland, and it was a luxury used car dealer in New Jersey. I took a big risk not inspecting the car in person or having it inspected before buying it, but I couldn't resist the price and the guy was very knowledgable about the car so I took the chance. It turned out good for me, there was only one flaw in the engine that he didn't mention but I was able to fix it myself. But it was the type of omission that could have cost your average person $1000 to fix at the dealer.
My best advice is to be very cautious (obviously). Inspect the car yourself or pay a company to inspect it for you. Depending on the amount of the purchase, it should be worth it. Of course, if you're buying a $350 Rabbit as a beater or something like that it would not be worth paying for inspection.
Don't expect the car to be as perfect as shown or described. It shouldn't be far off, but expect a few flaws not mentioned. These are used car salesmen we are talking about. Their job is to move cars as quickly as possible, for the most amount of profit. They are not going to donate any information that's not obvious and could potentially lower the sale price.
Don't bid too high on the car just because you are scared you may lose the auction. Many completed auctions are never finalized because the person either did not intend to buy the car or something falls through (or it's a fake bid from the seller trying to get more money). My friend had sold his Porsche twice on eBay without anything materializing. He ended up offering it to the next highest bidder, but couldn't make that work either.\
def have it inspected and use the carfax also, then look for people with good feed back. I've had a couple friends who bought cars off ebay and they're pleased with the experience. Like was said, be careful, ask questions, have them send extra pics of certain things you are not sure of or would like to see better and use ebays services such as inspections etc...
Well, don't sell anything to my Dad. He bought two cars off of ebay (a Porsche 911 and an old Studebaker) and he ended up suing both parties. He's not an attorney, and he represented himself, but he's pretty smart.
"As is" can end up being "as represented" to some old crank like my Dad. A good thing to remember if you're selling something.