Value of a 29,000 mile 2009 650i sport?

[mmirin]

Black on black, 19" sport rims and dark wood package. Excellent condition, always garaged but needs a paint correction due to use of a California Duster (swirls).
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I know the history of the car since 2012. A friend of mine bought it (upon my referral) from a dealership in Houston with 22k. It's had one oil change, and a new battery since then. Says it's always started (except for the dead battery from him leaving the key in it) but lately the passenger side door wouldn't open and then would. It also had a low coolant message. I need to go inspect the top, I think it's mostly been parked with the top down.

He's basically offered it to me at trade-in, which he says is $13,000. I think that's a bit high considering the possibility of some major engine resealing down the road.

I'm coming from a dual E38, and M3 household.

[Timm]

That sounds a tad expensive - in the UK we are now at entry-level prices of $7000 - everyone is scared of the problems such as valve-stem seals, oil leaks etc