Look at the picture, the prices are for each number, next to the item name.
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Please select a corresponding number from the illustration below to view the details of that part.
1) Light bar 2) Light bar Stud 3) Light bar Nut
4) Lamp 5) Lens 6) Roof lamp bulb
7) Wire harness 8) Wire connector 9) Cover Light bar
10) Cover Screw
So the price of whole thing is when you add them all up, which will cost much more than a assembled light bar. The purpose is probably to buy stuff that has gone missing or broke etc..
This reminds me, I wonder if anyone hooked up one of these bars facing backwards!