Ok here's my take on these have had all of them and only keep one.
Black Magic Bullet - poorly made may just be quality control issue but the first one I had pretty much exploded on the first use.
Mothers Power Cone- very nice product that is easy to use but made better with the extension that comes with the mini powerball, if you get both that close to a $50 investment. Is it worth that much? Probably not but still useful non the less, it does a great job on wheels and makes the usually tedious task much easier. I'd like to see the Power Cone packaged with the extension for the $25.00 it retails for now.
Innovative Products Bufferstick - great price got mine for $17.00 on sale, cleans a bit better then the mothers which is better a polishing. The Nice thing with the bufferstick is you can clean with it then pop on the micro fiber cover and then polish the clean wheel. For the money I prefer the Bufferstick, it has more versatility then the power cone. The only thing I'd like to see changed with the Bufferstick is a slightly longer rod to be able to do deeper rims.