I used to own an AK parts company. So I was buying more than a 100 kits at a time. I had a pretty nice collection of bfpu stuff. But eventually sold it all off. I built AKs too for many years. I also collected other kits. I had a dshk kit for awhile. Which is a huge .50 cal anti aircraft gun. Mp34s, swedish k, soumis, ppsh41 etc. Etc. And a ton of parts, old leather slings, etc. etc. I had a pretty large collection. But my wife had a major heart attack and eventually heart transplant. And I had to sell it all off.
I was trying to learn how to weld. Had the whole set up. But sold that off too.