Tennis balls for targets ($2-3 for a 3-pack)
Random damaged soup pot ($0 and an afternoon of "ping!"/"ding!" plinking)
VQ parts (varies, but most were <$20 for my mkIII, I have more on the way for a 10/22 and P22)
Sam's bushing for mkIII to delete mag interlock ($10 each)
Ultimate Cliploader (I think it was $21, but I'm including it anyway!)
Otis cleaning cable (Part of a $25 set, but since I didn't need half the brushes, it counts)
Craftsman toolbox for a range kit ($19)
Brass punches (~$2 each)
Brass/plastic hammer ($10-15)