Perhaps Amtrak? Since the cost of a bike is one price, add the wheels and it is surely into the oversize pricing bracket for UPS/bikflights

Per their website :Regular bicycles and unicycles may be shipped on Amtrak Express. Bikes must be securely packed in a box; you may bring your own box or purchase one at the station (call ahead for details and to make sure that boxes are available). Bicycles are generally exempt from Amtrak Express size requirements.

I believe the Amtrak boxes cost $10 and all you need to do is turn the bars and remove the pedals. Since the boxes are huge you should be able to add a spare set of wheels.

Downside is you have to get to Amtrak station and buyer has to get it there.