You can try places like rock auto, sometimes they have old stock for sale. I believe someone said they recently got usa made drums in a raybestos box from NAPA but it was the luck of the draw.
Just bought a bunch of closeout brake hardware kits and all the closeout wheel cylinders from rockauto for my fleet. Everything was OLD stock bendix & ac delco, I about fell over when I saw the wheel cylinders (delco) were all "made in usa" and even the casting said "made in usa" on them.
paid $4.50 each for the cylinders, the chi-com replacements are $20 each from the store and they last about 1 brake job before seeping