BMW performance suspension:
so 450 eur
BMW M Sports suspension:
price is not listed in etk but its 370 eur in Germany.
for bot kits you have to order some other part depending on what kind of suspension you have. for example:
E90's up to 06/2006 with Sport Suspension (S226A=Yes) must also order 2 front guide supports (31306775098).
E90's up to 06/2006 without Sport Suspension (S226A=No) must also order rear stabilizer (33556764426), front stabilizer (31356766288), 2 front guide supports (31306775098), and new springs.
E90's from 06/2006 without Sport Suspension (S226A=No) must also order rear stabilizer (33556764426), front stabilizer (31356766288), and new springs.
E90's from 06/2006 with Sport Suspension (S22A=Yes) require no additional parts.