Under Tank Heaters - Exo Terra ?

i'm running an exo terra desert on my snake's warm side, hooked up to a thermostat of course. i'm planning on getting a rainforest one for her cool side cuz its gettin' too cool if i dont run a space heater in the room & that's gonna kill my electric bill cuz those little things suck up so much electricity it's not funny! from what i can see the rainforest ones arent supposed to get hotter then 85 i believe but i'm gonna hook the one i get up to the thermostat too just in case.
cant end up with 2 warm sides now can i?

Here's a better discription of what I got going on:

I have a glass tank, 2 hides, one large glass water bowl, one small glass bowl with moss in it to help with humidity.
My exo-terra, medium, uth is under tank (duh) with hydrofarm t-stat under tank and under heat pad. My t-stat is set for 93%
I have one layer of newspaper substrate
My digital therm/hydro reads @
hotspot- 92%
ambient- anywhere from 79-81%
cool- %78
humidity is 50% bumped to 70% when in shed

I also have a 100 watt bulb to help with heat because this is all sitting in a room that stays usually at a constant 68% (my husband is cheap and waaaaay hot blooded and apparently my comfort isn't all that important, haha)

Hope this is more helpful, if not, oh well, haha.

I'd go with Zoo Med, better quality to me.