Depends on how anal you want to be about the retip. For instance, most cartridge manufacturers want you to sent the cartridge to them for repair and they are expensive. But if you have someone else retip and try to sell the cartridge later, chances are resale value will drop.
Deals? I like listings with broken cantilevers or missing styli, and I have sent a few of these (including ones I broke myself) to Steve Leung of VAS Audio. Steve is an incredible EE with pinpoint expertise and materials for proper quality retips at reasonable prices.