A pre-wired Ranco analog controller can be had from morebeer
for $55. I didn't comparison-shop so you may be able to find it for much cheaper from ebay or other places.... or you can get the digital version from morebeer
a basic 2-corney keg system from midwest supplies
can be had for $200. You may be able to get it cheaper from other sources as well.
I have the Love Controller pictured above. It's pretty easy to wire up, but if you're comfortable doing that, the Ranco controllers are pretty good too, from what I've read in these forums.