Williams gun sight has some 24's in their used gun section, but they all push $500.
I saw a used 42 at metro gun & pawn in Richfield MN and I believe they sell on the auction sites too.
Good luck. I have a 12 ga 223 mod 24 for my truck gun and thought of getting a 20 ga 22 or 22 mag and I pucker at the prices too.
