If they're certain it's the power supply get the serial number or any info on the actual power supply itself and take that info to any electrical wholesaler for a quote (L and H, cetnaj, cnw etc), then call up a few different sparkies and ask if they can change a power supply in a speaker, they shouldn't charge anymore then $80 an hour and my guess is it should take under 15 minutes for a sparkie to change a power supply... I have no idea how anyone could quote $1000 to change a power supply...