I just had to have my drivers side HID replaced due to a wreck, and the itemized $4K+ bill I received had a replacement 08 GT500 HID light listed for $1100. $525 might have been the option price, but what's the option price for the Recaros that have a $3000 FRPP price tag. Might have been where OP got his figures.
I've seen the complete OEM HID conversion kit for under $900 new including a pair of OEM Ford headlights, ballasts, bulbs, and wiring harnesses. Its not those cheap illegal HID conversions, but all OEM parts. Its hard to believe one headlight assembly costs more than the conversion kit that uses all OEM parts.