I'm not terribly familiar with used BMW prices, but do wonder if you can find a 2009 335 Ci for C $15,000. In general, once BMWs are $15,000 they don't tend to be reliable.
That said, the BMW 1-Series is also worth a look. It will be less expensive and since it is smaller and much lighter it handles with more agility. Soft top instead of a hard top, though (which is one reason it weighs less). If you can live without the power of the turbo engine the non-turbo will also be less expensive and less likely to require expensive repairs.