the best advise i can give someone is to look over the equipment in the wiki, and really get a feel for what it does (example, the freestyle is a 128 controller, which is great, but you need ssr's for it to communicate with which is added cost) then look in the current, and finished coop threads for the hardware you're interested in.
It'll give you an idea what's usually offered in a coop, as well as what to expect (ball park) for price.
YMMV