I love McMaster-Carr...always have.
However, their 3/8 x 3/16 'polishing' ceramic angle-cut cylinders costs $32 for ten pounds.
That's a good size for (say) 45/70 and other similar straight cases, but Kingsley North can equal that...and KN will sell it in smaller packages. You probably can't use ten pounds, anyway.
Their #2 burnishing liquid sounds like a great product, but at $82 per bottle, I think 'citrus degreaser' from Home Depot is good enough. They don't even say how big the bottle is...
Their porcelain spheres might be a good deal for bottleneck cases, but I didn't look at them very close.
CM