When I bought mine, there were 3 separate part numbers; the hitch, the wiring harness, or both packaged together. It was cheaper to buy the combination, and I paid around $600 at the time. I believe the harness by itself was around $200 then. It may have gone up in the years since, but I wouldn't expect it to be anywhere near $1000.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue