jacman, carelesslove, here!
As you see from the responses from your post, there are a lot of ways to clean your brass.
You should take note that there is a clear cut difference between cleaning and polishing. Regular old corn cob media will clean just fine. This gets the grime, bullet lube, and powder residue off your cases.
To make them really shine, polish them with clean media, with some type of polish added. NuFinish (automotive cleaner) works quick and is cheap, but the real trick is to keep you polishing media separate from your cleaning media. To see the difference, just pour your cleaning media out of your tumbler and look at the gunk stuck to the walls. This will contaminate your polishing media and reduce its' effectiveness. Also, cleaning should take 30 minutes to an hour. Polishing takes a lot longer.
Clean ammo just looks better. Remember to scrape out your primer pockets - your primers will seat more consistently.
-carelesslove