I think you should get guidance from craigslist rather than cars.com
I see tons of E53's in my area and they sell for peanuts, if they even sell those cars.
Close to 200k miles they sell for under $5k.
In 2009 I traded in my 2001 E53 with only 99k miles at the time, for $9000, premium package, surround sound, tow package and a ton of other goodies.
I imagine it would be less than $5000-$6000 now with the same mileage.

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2012 X70 XDrive 35i