well for $50 i can have a pair of heating pads in the size i need... can i set up flexwatt for that little?

i am picking up a used zoomed thermostat tomorrow from someone very cheap, i was going to run the rheostat after the thermostat... i'll set the rheostat for ~95*, then dial it back to 90-92 with the thermostat. if the thermostat ever fails it will go up to 95... low enough that it wont hurt anyone but high enough that i'll notice.