in bulk will be similar if not the same as 'shooting' related media and cheaper.

If it feels like concrete chippings sell it to Loiner on here :-) He uses all sorts of stuff!

Joking aside it should work fine - the brass doesn't get high speed blasted, just tumbled.

Start by tumbling 20 cases for a couple of hours then check if they're bling enough. Repeat as necessary.
HTH

Col