One big reason I would never buy a vehicle via a private sale or out of state - having to get it inspected.
Unless you know an inspector who is straight up, you can be in for a bigger bill than just the fee.
Particularly with older vehicles, they may be safe, but how much will you end up paying to get it through inspection.
That should be a condition of sale, vehicle passes inspection.
I'm lucky in that my son is a MD inspector. I'm getting him to go over mother's car before I sell it for her, that way the buyer doesn't have any surprises. She was always meticulous with it's upkeep, so I'm sure if there are any problems they're minor, I'll fix them, and add the cost of parts into the sale price.