If you buy it now, it's probably still under factory warranty. The miles are plenty but the years gonna end real soon. Therefore, get it now if you really like it, then go to a trustworthy dealer, get an inspection to fix everything. Then you're good to go. If you wanna keep it long, I think it's also best to get an extended warranty from BMW. You know, the navigation alone will cost you ~$4,500 to replace.
2009 BMW 650i Cabrio (daily drive)
2011 Audi A4 (groceries, bully, road trip, winter beater, family car)
BMW CCA ID: 473647