I recently got some Pearl Izumi AmFIB MTB covers, around $50 at the LBS. They are just like Az B said, "it takes a little time to get them on correctly, but they fit and work pretty well." I'm trying every year to punch through more of each winter. It's my first pair of booties, and since I got them it hasn't been really cold. But my feet are definitely warmer. Also they have some water proofing. The trick getting them on is to figure out how to get them to slip over the shoe's tread knobs. Also pull from the bottom holes and not any where near the zipper.

Another thing, somehow these things make my feet look really really big. I mean like four sizes larger big. They are supposed to be skin tight, so where does the bulk come from?