Here's a very common front wheel auto bearing. They are only $12 new at a NAPA auto parts store. I'm sure at a salvage yard you can get a used bearing + disc for ~$15.
I got a short section of common 1-1/2" and 2" pipe from Home Depot (strong and cheaply available in 10' lengths, enough for a 3-drum Savonius), plus I connected them with a bell union. I took it to the NAPA and compared it to common bearings to find a bearing that fit on one end or the other.
This one is a "BR5", and I was assured it came on too many cars to list, such as ford trucks, GM, Dodge, etc. It fits OK, but a little loose on the 1-1/2" pipe, so I may shim it with a wrap of sheet metal.
I don't know if this is the best option yet, this picture (taken just now) is as far as I've gotten. The plan is to have a '68 Ford Mustang disc sit on it and attach a 4-foot-ish wooden disc to the brake disc. (late 1960's Fords have the outer bearing race and the disc as one piece)
I imagine a simple sealed pillow-block bearing on an "L" bracket will be enough for the top. (look at the "variable pitch" pics from lforbes)
I want to identify common, cheap, and robust parts that can be used in a configuration for a VAWT, a 2' Turgo micro-hydro, or a 6' Poncelet water wheel.
I want to be able to raise a 3-drum Savonius on the middle of three sections of pipe (=30') with guy wires from the peak to help stabilize it.
I want it to be break-down-able to fit all the pieces in a normal truck, and for it to trickle charge a remote 12-volt system for LED lights and music.