Many factors are to be taken into consideration, much will depend upon geographic location, private or commercial seller, operational and cosmetic condition, whether or not the unit is original or restored (including the origination of service) and native voltage operating requirements. The rarest type, universal selectable 110v/120v/210v/220v/50Hz/60Hz voltage Technics Sp10Mk3 power supply will most typically demand higher prices than the most common 100v/50Hz/60Hz power supply or even the less seldom seen 120v/60Hz North American model. Considering the vital role of the Sp10Mk3's power supply, which of course contains the primary logic, drive and controller boards, its value will well exceed that of just an orphaned Mk3 motor, platter unit. I am afraid there is no etched in stone black and white answer, however, the market will usually dictate the demand and subsequently the asking price of rare and desirable components such as this.