For a first timer I recommend that you don't buy off of Ebay, too many traps. 
A lot of eBay cars are misrepresented, or a scam. Many times they just want to get your deposit and run. Here are some guidelines I use. Others may wish to add their own...
* Watch out for auctions that say you must be "Pre-approved", or auctions that want you to call someone before you bid. Never give out any of your financial information, period. They may try to tell you that unless you can prove that you have the money, they won't allow you to bid. Run away as fast as you can.
* Watch out for sellers that have 0 or low number feedback. Sometimes scammers will hijack legitimate accounts, or they will set up bogus accounts and buy a few things to give themselves a good rating.
* Be very weary of deals that are "Too good to be true". Many time scammers will cite financial problems as the reason for selling the car, but don't fall for it. If someone needs to sell a $50k Cuda for $9k, all they have to do is park it outside and put a sign on it, and it'll be gone in an hour. No reason to wait weeks to sell it on eBay, no matter where they live.
* Use the mileage search option to limit potential vehicles to within a distance that you are willing to drive to look at the car ahead of time (You just have to be patient until something shows up, believe me, it will), that way you can go and look at the car. If it suits you, discuss it with the owner and make an offer (It will probably be close to or at the "Buy it Now" price if there is one). Most legitimate sellers really want to sell their car, and use eBay only as a last resort after advertising it locally for a while, so they usually include a disclaimer like "Car is for sale locally, so I reserve the right to end the auction at any time.". They will have a "Bottom line" though, and if you make your offer too low, they may just decide to wait it out to see if they can get more. They can always decide to take your offer if the auction falls short, so they have little incentive to take a lowball offer from you ahead of time. If you put down a deposit in person, get a receipt. Check the title or ownership papers before you put any money down.
* Don't wire a deposit or funds to a seller. There is no way to reclaim the money. Paypal is a little safer, but not much. Neither is using an "Escrow" service, as they can be faked.
* If you really want a car that is far away from you, call an inspection service and have them check everything out, including proper documentation (Proof of ownership). It usually costs $100-$300, but it's still better than losing a $3000 deposit, or buying a car based on photos that are 20 years old or photoshopped. Time may be a limiting factor in auctions, however. Most inspection companies can just jump up and inspect something at a moments notice.
* Many second chance offers are bogus, so don't reply to the offer, but instead, contact the original seller through eBay. Remember that you have no protection at all if you buy outside of an auction.
* Be leary of foreign sellers. Many foreigners buy cars here, but few try to sell them here because they can usually get more for them in their own country than they can here, especially when you add transportation costs. Canada is probably an exception, but still be careful.
* Be suspicious of everyone and everything. Unfortunately, it's not an honest world anymore even though there are still honest people in it. I've heard of at least one instance where a guy sold someone elses car. It seems the owner was on vaction for a couple of weeks, so the scammer broke into the guys garage, took pictures, and offered the car for sale at a great price in an auction. He told the prospective buyers that he had lost the keys, and he could only provide a bill of sale. The guy who ultimately bought the car sent in a rollback to remove the car, and he paid the guy cash. The scammer provided a bogus bill of sale with a fake name. The buyer wound up getting arrested for vehicle theft, and spent some time in jail, and a lot of money trying to clear things up. The scammer ultimately got caught, but he didn't own anything, and had already spent the money on booze and drugs, so the buyer couldn't reclaim any of his money.
