Look for items with a variable speed, such as a treadmill has.
Not 2 or 3 speed, but variable speed.
The item does not necessarily need to have a brushed DC motor to be useful.
I have a big 3-phase PM motor came out of a single phase input industrial sewing machine.
It is similar to a regular AC servo motor.
I would post the photo, but my files are apparently missing.
"Ugly30", if you can find it.
The Harbor Freight Mini-Lathe is variable speed, and has a brushed DC motor that I think would be useful as a small generator.
Look for the speed control knob, and you might find something good.
G-