100 Dollars for a 20 dollar thermostat? Someone is ripping you off.
Go to most any hardware, or Big box home Impreovement store, for the furnace there are basically 3 types of T-stats
Electronic (Some of these may work but I would avoid them)
Mercury bulb Do not buy this type, requires rig be PERFECTLY level every time at least in one direction)
Bi-metal with contacts.. Tad hard to find but this is the cheapest thermostat made, it is also the best for RV use less you need the advanced (Automatic setback) features of the elecrtoinc ones.
