If you have time you can make one. I made one out of scrap\junk wood. I drew the pistol profile, cut plywood (and I think some of it was laminated wood) and glued on leather so the pistol would not get marred. It's not a real pretty device, but very functional. I just clamp it to the shooting bench.
I wanted support all along the back of the grip so nothing would crack when loading. So far, it's worked out well. The pistol stock in the photo (less the components) is my current 50 cal and the one in the background is my current project.
