I bought the ones from Makarov.com. I sanded them down, stained them, and refinished with polyuretane. I have only shot the gun a couple times after buying the grips but they seem to be holding up OK. I believe that they are made from three seperate pieces of wood which are then glued together. I put an additional bead of glue down the joints on the inside.
I posted the same question a couple months ago and this was all I turned up.