Depends what year, 80-81 is the best. Nothing more than $3000. You will have to put money into whatever you buy, so stay below your budget. I bought an 80 528i, in great condition, for $2250. Within a couple of months many unforseeable, by me at least, things have gone wrong. The upshot is that these cars are very fun to work on, and doing it yourself gives you alot of insight into the great engineering that went into these e12's. Good luck.