I use a TRUE GDM12 ($500 used) modified to work with the BrewPi. Fermentation temps stay within .2 degrees. Here is a screenshot of an iPhone app I wrote to monitor the temps. Currently I am at day 14 for a nice Belgian IPA 68 degrees.
Thanks for all the discussion, I Just order a small BIAC, delivered January. In the mean time I am making a PID controller (Overkill) to pass the time. I will update my progress.
KnotAByte