I really like the Nu-Finish, I've used a number of other car/metal polishes over the years and some of them (particularly Meguiar's) give a brighter, shinier, almost chrome-like finish to the brass, but nothing I've tried seems to keep them looking good and tarnish free as long as the Nu-Finish does.
I also like the used dryer sheets to both remove crud and keep the media and tumbler "static cling" free. I cut the sheets up into strips about an inch wide. This makes 'em trap more dirt (at least they LOOK dirtier after use) and also seems to affect tumbler operation less (i.e. the motor doesn't "load up" as much).
I'm about as cheap as they come, but I only tried washing cob media once. The labor and drying time involved were both excessive and the end results wern't very good either. As I see it, the main advantage (other than the really bright, smooth finish it gives brass) that cob has over walnut is that it seems to actually absorb a lot of the crud it removes from your brass. Since a lot of the stuff you're trying to get rid of by washing isn't on the surface, cob doesn't clean up very well.
I've had somewhat better luck with cleaning walnut media. I just put it in a loose fitting, very fine mesh bag and dunk it in a five gallon bucket full of hot water and a little Simple Green. Then I "agitate" it for a few minutes with a canoe paddle or baseball bat, rinse several times in fresh water and toss the bag on top of my central a/c condenser unit to dry.
I've only done this a couple of times when I was totally out of fresh stuff and had cases that I needed to clean ASAP. It works, but the "reclaimed" media doesn't work as quickly, polish as well or last as long as fresh walnut.
I look at washing media as sorta like trying to get a full week out of a "Five Day Deoderant Pad". It might be possible, but it's sure as heck not what I'd call a "best practice".
Nowadays I just go by a sandblasting supply house and buy my cob or walnut in 50 pound sacks.
Either one costs me less than 22 bucks and they're available in various meshes (I always buy the smallest they've got since Berdan flash holes plug up very easily).
I always ask if they've got any "seconds" (usually bags that have leaked a pound or two of media). A couple of times I've been able to purchase the "short" bags for 50% off.
Ten bucks plus change is a pretty good price for almost 50 pounds of media.
On The other hand, DO NOT buy any water damaged cob media!
The one time I got a bag of water damaged cob it was very badly mildewed and the dust it produced probably would've given Superman a fatal case of black lung within days. I ended up throwing the whole bag away after running one load with it.
I've never purchased (or even seen) any water damaged walnut, so I have no idea what it's like. I also have no intention of finding out, at least not first hand.