That sounds about right. Do a test drive of atleast 20-30 minutes. Check every little thing that could possibly bring the price down interior, exterior, under body, under the hood, tires,ect if all is in good condition buy it. Then change the oil, coolant, all filters, O2 sensor, brake pads,windshield wipers, ect. write down the miles at which you did it so you know when to change everything. Have it BMW certified and have fun.
If you can't talk him down request for it to be taken to a proffessional detailer.