Captain America, I love this magazine release, it stays out of the way and is a positive release. I also modify the bolt hold to auto release when you pull the bolt back and release it.
22/45, A good friend gave me 4 stocks, and 5 barrels and I have collected bolts, trigger groups, bolt handles, pins, etc. over the years (I just knew pack ratting these things would pay off someday). Some of the trigger groups were given to me by customers when I installed the BX trigger in their guns and did other mods. They had no need for them and they didn't want them so they gave them to me. In turn I'll do little things for them at little or no cost. I got this stock for $20 at a yard sale.
The biggest cost is the stripped receivers but you can find them pretty cheap if you take your time searching. Some times sellers will give a good price if you buy more than one at a time.