Popular choice for springs only, £205.00 delivered for members, labelled as 30mm drop front and rear but its closer to about 27/28mm...
More than that (on springs only) and I think you'd be running into major difficulties. One thing to note though is that standard wheels look rubbish when the car is lowered. If you aren't planning on changing the wheels it might be an idea to look into spacers too.
cue CS stage left to centre with price!