I mean its up to you but the kit is not much cheaper than coilovers. I would save up money and get some nice midrange coilovers like ST coilovers or BC BR coilovers.
If you get springs and use stock shocks,you will eventually want/need to upgrade your suspension. Good Luck!
2005 M3 Jet Black SMGII
Exterior:ZCP/CSL Wheels Carbon Fiber CSL Trunk. Remus Exhaust. Black Exhaust Tips. Matte Black Kidney Grills and Gills. Engine:AFE Intake, TurnerMotorSport Lightweight Pulley Power Kit, Supersprint Headers (Catless) 1 AR20 and 1 magnaflow resonator on stock mid pipe. Supersprint X-pipe Activeautowerke Tune.
S85 Swap in progress est: Late 2013 :)