Some suggestions:
you could probably find all of the components from a donor in a bone yard someplace. There are some on-line sources for checking used parts availability. Here is an example. The utility in this case is unknown:
http://www.car-part.com/cgi-bin/search.cgi
2) I found a place in Seattle that will retro-fit seat heaters for most any car. The cost was about $600 per pair. They weren’t as good as the MB heaters but worked well. I was told about this from a SA at a MB dealership. It is entirely probable that someone near you does this as well
3) as mentioned, places such as Target, larger department stores and probably pep boys and similar also sell pads which have both heat and massage options. Very inexpensive
Good luck!