Stay away. Thats' coming from three people who have coilovers. As P5UML has said, you're MUCH better off going for reputable springs like HnR (greater drop, harsher ride, no adjustment) or Eibach (medium drop, better ride quality compared to HnR, again no adjustability). Taht or save up. It seems a lot of money to spend i.e. £650+ for decent coilovers .. but do you really want to risk driving your beautiful car on budget suspension?
Now: E92 335D
Gone But Not Forgotten: E90 320D Alpine White