Sounds like it's probably in pretty good shape. With only 64,000 miles on it, $2500 sounds like a great deal to me. My 1987 325e has over 260,000 miles on it, and I paid $1500 for it. These cars last forever and are an absolute blast to drive.
One tip - find out if the timing belt has been replaced. They are supposed to be replaced at least every 60,000 miles. If it hasn't been replaced, then you'll need to do it - if the timing belt breaks on these cars, it destroys the valves and will require a head rebuild or replacement.
These cars are easy to work on, and parts aren't all that expensive, especially if you order them off of the internet. The BMW dealers can still get tons of parts for these cars as well if needed - my local dealer actually
stocks lots of the parts for the E30s and will even beat the mailorder or internet prices. Having only prior experience with American cars before getting my 325, it's amazing to me how well BMW does in keeping the parts available for their cars.
This is a cool place to hang out - you'll learn alot. If you have any other questions, we'll all be glad to help out.