Are you doing autotrader or ebay?
I've purchased cars through ebay twice now.
First one was smooth as silk since it was from a local dealer.
Paid an additional fee for all the documents and tax/title to be filled out by them, and drove out a day later.
Second one was a private seller and pretty difficult on account of the seller. I was planning on financing it through my company's credit union which is based out of CA. I'm in TX. And I TOLD HIM THIS.
This guy is the president of a local bank and was selling the car himself on behalf of his daughter - who I presume probably couldn't do it herself or daddy is just very overprotective.
I won the auction, went and left a 1K deposit (which he cashed the first day) and told him to wait while my credit union finalized the paperwork. He has power of attorney to sign on his daughter's behalf yet didn't understand some documents required the actual signature of the person who was on the title. This wasted a lot of time. He got very impatient with me because the credit union was taking so long with his demands and he had already signed everything, the exception being some docs for his daughter. C'mon you're a banker. You should be familiar with what they have to go through. Let alone have the common sense to know unless you fedex documents, it takes a couple of days for them to arrive via US Mail, and may take a day or so to process.
He kept emailing/calling me to see what was up, and I told him I did my part, now just wait on the paperwork to wrap up in CA. They'll FedEx you a check in about 2 days. After telling him that, he still had the nerve to change the negotiations and DEMAND that instead my credit union wire the funds to him immediately at his bank.
The guy was pushy and demanding during the whole week it took to wrap this up. Again - it takes time to mail stuff and recieve it - but hey once it was over he was back to the nice guy he was when I first met him.
I also remember when I was about to drive the car away he stopped me and asked "Oh one more thing...you're not going to turn it into a rice rocket are you?"
The most difficult thing to obtain was the title and bill of sale.
I needed the title to send to the credit union (they finance it, so it becomes their car) and the guy would understandably not give it up. It took some phone calls from the credit union to make him realize that was necessary for the process, but we got around that with a copy until I was able to change the title to include them on there as the lienholder. I had to send that updated copy to them as well as proof of registration/reciept which doubles as a bill of sale. I just wish I had told the DPS that I paid less than what I actually did due to the tax and the fact they don't really stop to verify what you paid on a used car.
Insurance wasn't a problem (aside from the usual salesmen) and that was done before all of this. I just had to being it by and show them the mileage and condition of the car after all was said and done.
So basically if you finance, you may have to do some of the paperwork yourself (go to DMV/registration, Insurance, Title etc.)
I chose to do it myself because my credit union would have likely added some of those fees to my loan ammount. Looking back now, it's worth it if you don't want to waste the time standing in lines.
Good luck on your purchase!