Here's a tutorial on making slipper sock bottoms: http://www.myzigzagstitch.com/2008/01/07/how-to-do-it-slipper-soles/

They always seemed expensive to me, but making your own might save some money.

 That looks like a good site.  Thanks, Pat.

The ready made ones are expensive.  I looked around at the ready-made ones and they seemed to be around $30.00 a pair, and 19.95 for just the leather soles.  I know that price is probably because of the leather, but still seems like a lot, especially if it was thing leather that might not last too long.  

Edey

10 years ago i had mukluks wish I knew how to make them i would make them myself then try to hunt those suckers down kinda hard to find them ..

Edey:

I know that price is probably because of the leather, but still seems like a lot, especially if it was thing leather that might not last too long.  

She said she got the suede leather for $5.99. I'm not sure how long that would last, though. You might be able to get leather scraps that would work as well.