That's pretty low! I know around here they go for anywhere from 2500 to 4000. Is he someone you know? Such a low price might be a red flag that it's had or has some kind of problem and he's trying to pull a fast one. Once again, I recommend taking it to a BMW mechanic. They should do pre purchase inspections, most reputable shops and dealers charge a fee but better to pay a small fee then pay 1500 only to find out later something's wrong.
Wherever you go, there you are