If you're looking to do two-stage temp control I would recommend the Ranco digital control either through MoreBeer or Brewmasters Warehouse (cheaper). I just bought one myself.
There's also the digtal Johnson controller but it will only control one heating/cooling device. There is the analog version or the digital version. I prefer the digital version though since it seems to have a better accuracy for temp control for fermentation. I use the analog version on my keggerator.