I cannot find the pulley anywhere , with luck someone else will.
Also I would not order a motor till you get the blower wheel off of it as often it has to be destroyed (seizes to the shaft)
If the pulley fits tightly onto the shaft you could try drilling through it and the shaft and installing a pin.
Install a lock screw in the pulley. But unless you have the proper tools (tap, etc.), this could be a no go.
I do not think this was just a sales strategy. More likely it was to fix the same problem as you are having.