Cost too high? Do the math.
3 mats + 1 canister = 12 hours for about $6

Thats about 50 cents an hour I'll pay that anyday so I can sit still and quiet in the stand I've worked so hard to set-up. The ThermaCell is the number 3 thing on my list. Bow, release, THERMACELL!!!!

If you haven't tried it yet, trust me. It is worth it's weight in gold. For all the scent skeptics. I had 2 deer walk within 10 yards of my stand yesterday with no signs of spooking. One even completely circled my tree!