4. Buy aftermarket for more performance for your buck.
If your warranty is up I don't see why you want to go with the BMW performance suspension, it is not worth it. Aftermarket will make a much bigger difference for the same price point.
Here are the best suspension choices for our cars:
http://hpashop.com/Suspension_c234.htm
I would personally do the M3 suspension conversion + decent coilovers if I were you to get a really great handling car.