A quick search for the part and it looks like $247. Saw one on eBay for $190, but it was pulled off another vehicle. BMW in my area charges $190/hr with a 1hr minimum. I would be in it for about $550 if I did it myself.

Today they quoted $650 to have it done with a 12 month warranty. I would check the other shop I use for pricing first before doing this.

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2003 X5 Steel Grey
3.0i e53