If you live in suburbia, there are several Thumblers tumblers on your street that have not been used in decades. They were purchased for polishing rocks. These can be had very easily [free if you are slick talker].
Thumblers tumblers are made by true square metal products in Auburn WA.
http://www.thumlerstumbler.com/
There is more info about the different Model B TT140's at Buffalo Arms [where I got mine]:
http://www.buffaloarms.com/ManufacturersProducts.aspx?MANF=1139
You can see there are 20 rpm drum speed model Bs and 40 rpm drum speed models.
I think you want the 40 rpm, and the ones in basements and garages in your neighborhood I am guessing are 20 rpm.
I have been using mine for Moly coating bullets.
I bought the Lyman Kit with vibrator, ceramic media, separator, and moly powder.
I still use the moly powder.
I now clean bullets, dry them, and put them in a plastic container, typically 8 ounce size, put some duck tape around the lid, and rotate for an hour in the Thumber.
For cleaning 150 pieces of brass, 5 pounds of stainless steel media [ round rods .041" dia, .255" long] with an ounce of Ivory dish washing liquid and a tablespoon of Lemishine, with hot water to the top.
Here is a video of me cleaning brass. It is 12 minutes long and the average view is 3 minutes. It is a VERY boring video. But for the Thumbers Tumber, skip 5 minutes in:
https://www.youtube.com/watch?v=Ou9kKhlXcJk&feature=plcp
If you tumble for 24 hours, the brass will look just like new, and need case mouth chamfering, just like new.
It becomes obvious that brass manufacturers are tumbling the brass with some hard media [not corn or Walnut].