Most local places don't really carry thermostats okay for snakes. You're going to have to get it online, but you could call around to pet stores that carry reptiles and ask. Don't bother with Petsmart or Petco or anywhere because they /don't/ carry them and if they do carry a ZooMed Rheostat it's more than useless for a BP. I had one and couldn't get the temps below 100 degrees.

And yes, the Acurite thermometer is popular because it's not expensive and works really well. Make sure it shows indoor and outdoor temps and humidity. Indoor for ambient, outdoor with the probe for your hot side, and humidity for... humidity.