I bought a Johnson controller.... Now I regret it. I'll sell you my analog one cheap, so that I can build myself another one of these:
I built it and loved it, total price was around $35, digital does heating and cooling, and will keep it within .1 degrees celcius.
The only problem is that ... its in celcius, which is not really that big of a problem
(Note: I regret the price of the Johnson controller, because it was expensive and for the price of it, I felt that it was lacking. Also being able to do both hot and cold is nice, but it doesn't provide that)