The more popular billet grilles are by Stull (10 bars) and the Trenz (16 bars?). The average cost is between $140-170. You do have to cut out your main grill to install. Take your time and use a dremel tool for best results. This is general info to answer your questions.
Trenz @ :
http://www.trenz.com/index.php
Stull: Check performanceproducts, I think it is there.