I think I've seen Kooltrons or their equivalent in Sears, for maybe
around $79 on sale, depending on size.  As I recall, the AC adapter
is extra.  They heat/cool +/- 40F degrees of ambient temperature,
i.e., trying to warm your lasagne in a snowstorm is NOT going to
make you very happy.  Conversely, trying to keep your turkey
sandwiches cool in Palm Desert may give you a bad case of botulism.

/martha