My brother just got a car through Craigslist. If you are going to be financing it, you will need to "Close" at your bank with the current owner. This will allow the bank to get the title instead of you since they will be carrying the loan. I think if you finance a vehicle that is being financed by the sell it turns in to a clusterfuck.

If you are not financing, bring a bill of sale and make sure he signs in the right spot for the title. I traded a vehicle to ChunkyMonkey and the title had been signed in the wrong spot and it was a pain in the ass. Not because it was hard to do, but because it took up so much of both of our time.

Good Luck.