as for what I would charge ... I have no clue. I have never gotten offers for my work. I just see something I like and I sculpt or paint it. as for what it is made out of here is a photo.
The box is 8lbs of white Polymer clay. It feels and acts like Oil based clay but will not melt, will not harden if left out and can be baked in an oven or toster oven. that box there was $34.00 and has lasted me over a year. Most of my large stuff is not solid clay but a foil body wraped in clay and then carved or sculpted for the full 3d effect.