I looked into getting that kit a long time ago. I talked to the guys at speedlab.com and they quoted me a price of about 1600 for the whole kit. Realistically, you probably wouldn't want to front lip or rear valence unless you want to do some cutting.
The potential to screw up the car when putting on the fender flares was a risk I couldn't take financially.
If you end up getting the kit, please post pictures! I am very interested to learn what needs to be modified to make it fit. I was thinking at LEAST drilling holes, and possibly some body rolling.
The fender flares are a simple matter of drilling, so any competent body shop should be able to easily install them for you. I'm not too sure what you mean by body rollling in relation to aero parts, but MrMark has already installed this lip on his car with some modifications from a local boat fiberglass repair shop.