Tube type ferrite core. These are low cost, but you have to have access to the end of the wire to thread it through. However, it is possible to stop it getting out of the motor in the first place. Most of the interference travels along the power wires as the motor body provides a reasonable degree of screening itself. As it moves along the wires, they act as an antenna which broadcasts the interference to the world.
Most electrical suppliers sell what are known as ferrite chokes or ferrite cores.
If you put a series of RF chokes along the length of the wires, the interference, both carried along the wire and picked up from outside, is attenuated at each. Do this and you may not have to spend another 200 on that glossy PCM radio.