I've never used the jar & pantyhose method, nor heard of anyone actually trying it, besides the author. I think I know the book you are talking about though. I believe you just leave it in a warm room, correct...? If you do that, you may as well just use a rubbermaid shoebox($4), some vermiculite($5) and some water($0) in a warm enough room. That would be the cheapest I can think of without providing extra heat. If you do need extra heat - A styrofoam cooler($10) and a fish heater($30) would do it. I have never used that particular method, but lots of people do and that seems like a fairly cheap way to go about it. 50 bucks ain't too bad

, and if you can find deals on those items(maybe at the Red Deer show...?), it could be cheaper than that. Lots of people here use the styro/fish heater method, they can probably provide more details/pics for you.