Centric parts makes them, you can get from any place that carries Centric, like RockAuto:
2000 Front:
More Information for CENTRIC 14337009
2000 Back:
More Information for CENTRIC 14337013
Looks like the fronts and backs might be the same for S and Base but I can't confirm...
Racingbrake also makes caliper rebuild kits including high temp silicon dust boots for track:
http://www.racingbrake.com/category-s/7185.htm