Can I use high face mesh to make an image?

I would like to know if this is possible and how to do it if it is. I have a single mesh, one I made from the asteroid tutorial (fasteroids http://davidjarvis.ca/blender/tutorial-21.shtml), that has been textured, colored, subsurfed, displaced 2 different ways and smoothed, all done with internal blender textures. When I render it , it looks just like I want it too. The mesh has 61,000 faces. This is bad for what I want to do but the look is perfect. I need to end up with mesh that has around 100 to 200 faces.
How can I take the finished look of this high faced model and turn it into a image texture that I can apply to a new lower faced model using UV? I guess the best way to explain it would be to peel off the complete finished face of the original asteroid, save it to an image so I can then UV map it on to the lower faced model. Can this even be done?

Have you tried baking your texture? Particularly the normals. You can then map that image back onto the mesh as a bump map. This video shows how to bake and remap a Node material as a texture, but its the same principal.