I'm just using liquid dish soap and hot tap water. Put a few thousand brass in a 5 gallon bucket and agitate by hand every 10 minutes. Drain and rinse after an hour. Started drying on cookie sheets in the oven at 250 degrees, but that was too inconvenient, so I lay a towel out on the trampoline in the backyard and let them air dry. Not a spotless cleaning, but better than tumbling. Quite frankly this is all less time-consuming than using the tumbler and having to use the media separator and then individually dump the media out of any cases that didn't dump it while in the media separator.
I got some citric acid to start trying out also, from the Mediterranean Imports store. According to the internet the brass will be very clean after a soak in diluted citric acid.
http://castboolits.gunloads.com/showthread.php?83572-Citric-acid-brass-cleaner
Eventually I plan on getting a cement mixer like GT did, and maybe even using the stainless steel pin media.