ecs tuning is in ohio and should be able to give advice.  the bimmerforums are a great place to learn from.  from what I have found so far with the e36's, is anticipate to spend 3-5k in a hurry for "bolt ons". 1kish for cams, 1-2k for valve train (solid rocker conversion), 500 for vanos delete, god knows what for a decent clutch, and plus ecu with a tune.  I went with the route of get it dead reliable and upgrade the suspension before anything else.   
if its the engine I think it is then tune, downpipe, turbo's, tuning, and your car will boogie.