I've recently brought a 320d M sport coupe. It's a 2008 with 80k on the clock. Running on non runflats and 18" wheels it's really comfy and handles well. I'd look at approved used cars only though as mine just had the clutch and flywheel replaced under warranty. It also had an oil/brake fluid service, new disks and pads all round, new tyres on the front. I paid £10,650 and have BMW's warranty so not to worried about chain problems.
My mates 2009 320d se has 215k on the clock now and only needed a clutch plate re lining and Xenon headlight bulb since getting the car 100k miles ago.