If you're going to buy a car that's older than you are, the straight-6 / manaul transmission BMW's built in the 80's run forever.
Notice how many of them you see still driving around in the Bay Area?
Now you know why.
For 2,800, you can find a late 80's 325i or is - those cars are pretty sweet and put out decent power.
A late 80's 5-series can be had for around the same price.
I've had both an 87 535i and an 86 325es and they were solid, tight nice running cars that were cheap to run.
I'd love to find a late - 80's M5, but don't have the cash or the room right now.
Avoid the 6 and 7 series.
Contrary to popular belief, certain model BMW's run forever and cost very little to maintain. These cars are excellent values.
Plus, you have the prestige of driving a BMW and they are fun cars to drive.
Just be sure to avoid the 6 & 7 series and any 3 & 5 series with an auto trans.
Also, be sure to buy a car that has service records and has had the timing belt done recently, otherwise, you need to factor the replacement cost of the timing belt into the purchase price.
Here's a few example's of them in your price range:
http://www.craigslist.org/eby/car/51499682.html
http://www.craigslist.org/eby/car/51290384.html
http://www.craigslist.org/sby/car/51456673.html
http://www.craigslist.org/eby/car/50998585.html
http://www.craigslist.org/sby/car/50874286.html
http://www.craigslist.org/eby/car/50558625.html
Note: A couple of the cars above were Auto trans, but they were just posted for an example of the type of car you can get in your price range.
Again, these cars easily go 250K and beyond.