Hey there,
One of my buddies has owned one for a few years and its been quite economican when it comes to routine maintenance.He usually takes it to Milroy but the quality out there has somewhat deteriorated over time,however there are ppl who know how to take care of beemers and most of the spares are readily available.
Beware of fuel pump issues as it would be a costly replacement.
Fantastic car to drive and to be driven in specially when the turbo kicks in in 320 D.
I hope you could go for the face-lift as it gives better fuel economy and power output.
All the best.Hope you will find one soon and enjoy the ride.