One way around the high cost of materials is to use modeling clay and plaster. Both are cheap; Dick Blick sells Klean Klay for a bit over a dollar a pound (he calls it Dick Blick Gray Modeling clay) and once you buy the clay it is yours for a very long time.
The process that comes to mind is making plaster piece molds of clay figures; then make plaster casts in those molds. Obviously it's not ideal as you have to be very careful of the mold release and the undercuts, or the mold won't release.
I like working in plaster. I have a bronze foundry but I make things in plaster too. Here is one I did a few years ago.
(I studied up on anatomy after this one, but still, I like it.)