I find low mintage 90% junk coins as well in my dealers bullion stock. But, if you look closely, you will see that these coins have been cleaned, which means they contain little if any numismatic value.
My local dealer offered me an empty like new 2 volume set of Intercept Shield albums with slipcases for ASE with proofs for just $20. I passed. Already have a set without proofs in a Dansco 1986-2010. If I were going to spend that kind of cash [to get all the proofs] I would buy gold instead.
I buy ASEs and 10oz bars. I have two proofs of almost every ASE issued by the mint. I don't buy the 100oz bars because they might be hard to get rid of. I stopped buying Morgans and Peace dollars unless they hAve dates or mint marks that add value. I've never sold any of them but I believe the ASEs and bars are good investments.