I've got a PC7424 orbital buffer. Orbitals are a lot more 'fool-proof' as opposed to the typical 'rotary' buffers.
I got mine from autogeek.com...they have many different sets with different pads, polishes, etc. You can pick from a variety of price ranges. You can just buy the buffer by itself for around $150.00 or so, but the package deals are better as you get everything you need.
Oh...and yes, my rims are 20 x 8.5" VCT Castellanos on 255/45-20 Toyo Proxes 4's. Only thing used to clean them is Meguiars Gold Class soap and my wash mitt...then dried to a shine with a microfiber towel.
Any other questions about the buffer, let me know. Or you can check out
www.detailcity.com for a whole 'plethora' of info regarding detailing.