Purchasing a car from a private seller. Nightmare.

Sometimes your luck goes the other way:

I purchased a nice Olds Cierra that had a terrible vibration under acceleration. The seller said the tranny was going out. When I got it home, it only needed a motor mount.

Purchased a non-running Ford Ranger with zero compression in all cylinders for $100.00. All it needed was a $20.00 timing belt.