When I damaged my tailgate in '01 and went shopping for a replacement, I found one off a dually, but the lightbar was missing. Ended up buying a new one from the stealer. Yeah, the wiring harness is priced separately from the bar, which is separate from the lights. And you can't buy the black screws from the dealer, they don't have them for sale. All said and done, it's close to $100.
I later found replacement lights at NAPA, but they weren't LED. Much, much cheaper at NAPA than at the stealer. The LEDs may be cool, and perhaps a bit brighter, but depending on the cost, you may be able to by several rounds of replacements from NAPA for the cost of one the LEDs. Sorta like the flourescent bulbs to replace your standard incandescent bulbs in the home. (Still too pricey to be cost effective. I only use them in hard-to-change locations. )
FWIW,
-Jay