WTD: Cheap 29er or 700c single speed or Fixie rear wheel

[Dave_H]

I'm looking for a 135mm OLN rear disc wheel to plug into the front of my Fat Bike to give me the option to run it with thin tyres.

So I want a cheap rear wheel with a screw on SS type hub so I can just take the freewheel off (or even better if it doesn't come with it) and run it on the front.