If you want 'set and forget' temp monitoring, I'd suggest a PID. You could build a box with one PID, SSR, Contactor, and temp probe for not a whole lot. It will let you program whatever temp you want (or, depending on PID model, set it to manual mode) and will do the rest for you. It will cost you more than the PWM or Ranco method described above, but would also give you more percision control of the temperatures.
Building a Bad News Brewery - eHERMS
2013 Brew Count:
10gal Southern Pecan Ale (Blind Squirrel)
5gal Ed Wort's Apfelwein
5gal Saison w/ Italian Honey (Resurrection)
15gal Irish Red (Bloody Knuckles)