Will you be using the yoke on a Star Wars cab or with a PC? The pots would be either 1/4" shaft 5K or 100K linear taper pots. 5k for use with the arcade pcb, 100K for use with a pc. If you're going to use the Dual Strike hack you'd want 5k pots as well. High quality are expensive, the best are conductive plastic and you'll pay around $50 a piece for them. Radio Shack has cheap ones, for better quality pots I'd try Mouser or Newark Electronics.