They are certainly asking top dollar for it. Based on the pictures on the website, there are several things I would want to look for. First, there is some staining on the wheels from brake dust. This, combined with the dust you can see leftover from the engine bay wash shows that the car may have been washed infrequently. It does look quite clean on the interior and the paint looks really good (from what I can see), so it may be that the car was garaged, not driven often and sat for a while in-between washes. Not necessarily a bad thing, just something to keep an eye on.
There's definitely seepage around the valve cover gaskets, which is normal, but take that into consideration with your maintenance budget. I'd also check the battery and voltage when the car is running. That's one thing I usually forget to check, but if the alternator hasn't been replaced before, it's probably going to come up in a year or so.
Besides that, since it's coming from a BMW dealership, they're going to have it in good running condition so you really shouldn't have anything weird that they would have neglected. Good luck!