I have 2 Ultratherms and love 'em.I use them with these:
http://www.amazon.com/Hydrofarm-MTPR...1409180&sr=8-2
Decent thermostat for under $30, and everything's worked great so far. I'll use heat tape and a nicer thermostat when I get a rack set up, but for single enclosures this setup has worked well for me so far.