It really depends on how much you want to spend. I've spent close to $4K on suspension parts and it was well worth it. I would recommend coilovers to start, then or at the same time, sway bars as already suggested. That said, a great mod is the M3 rear subframe bushings so if you are adding the rear sway bar you may as well add the bushings. GL...I wasnt going to spend much either but after each mod I found myself searching for other mods to improve the suspension.
