-Amen to that, TM 51!
I scored some 45 lbs of worn-out bearings from the work dumpster, as the A/C fan & pump overhaul progressed a few years back.
getting a few dozens of 12 mm balls at HRC 64 provides my lifetime's need of feet for my surface plate DIY measuring tools,
and the races are useful for precision clamping and parallels or even providing the hardened convex for a DIYed surface gauge...

Some tips: -Are you lacking balls or missing races? - Meccano Gallery
Grinding the feets (yuk, yuk) - Meccano Gallery

2 cents
Cheers
Johan