It really doesn’t take much, in my experience. Consider too, that you don’t need LemiShine at all to get them clean if you don’t care what color they come out. You can start just above zero and work up until you get a feel for it. For 200 pieces of 9mm, I’d probably use a chunk about the size of a marble. Not a shootin’ aggie, just a regular marble.
Hope this helps. There really aren’t any wrong answers, just that some are better’n others.