Heating system for Ghosts (and hissers)?

[femmephyllocrania]

So I recently went back to school and brought all my little creatures with me. Unfortunately I ended up in a room with two windows on the corner and it tends to get cold. I'm starting to worry for my creatures. So far they've been doing alright with it and once the main heat is on in the building it should be fine, but since this is New England and the temperature likes to f*** with people during any season I'd like some sort of heating system I can use for now while there are cold days but the heat hasn't been turned on. Something that doesn't require a plug would be good, since the cages are not really near any plugs (i can get another extension cord if it's absolutely necessary but I'd rather not) and not too expensive would be good. I also don't want something that's going to be so intense it cooks them while i'm in class. Just hot enough so they can function normally.

 

[Frack]

I use my internet modem as a heater for one of my roach enclosures, it actually works very well.

 

[cloud jaguar]

Or atop the computer monitor seems to create latent heat of about 90 degrees - you may need to put a potholder or something to reduce heat down to 80-85.

 

[hibiscusmile]

a radio, a tv, on top of a small fridge, anything electric you already have will let off heat.