The GM kit like Hale suggested is the best from what I hear...the kit is around 900 with shipping. this comes with Adjustable struts and lowering springs.
also to tighten up the suspension you can do strut tower bars, sway bars, trailing arms and poly bushings.
you can get a kit from GMparts direct for about 150 or for the better alternative the BMR parts will set you back about 500 or so.
there are alot of different setups you can go with...
personally i will be doing my whole suspension in a few weeks and I went with the following
KYB Struts
GMPP lowering springs
GMPP Sway bars, trailing arms, strut tower braces
I have the pogo retainers to stop the pogo (hopefully)
as well as all new poly bushings
all this cost me around 500 or so