I got one from eBay for a lot less than that. one of my rear sensors is bad so I bought one.I, too, called in my BMW dealership and they said it would take minimum 2 hours labour plus price of hardware.....

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JL
'02 x5 3.0i
-Black on Titanium Silver (354)
-Sports Package
-Smoked LED Side Markers
-Chrome Gauge Trim Rings
-Retrofit AEs (Favorite Mod)
-Front & Rear OEM 4.6iS Diffuser
-Front & Rear Fender Flares
-K&N CAI