I have a 120k on mine 325 e46 and it still feels really tight,its a great daily,does all you want,the key would be to find a car that has had service history.
Motor is pretty bulletproof,lower control arms at >100 k will probably already have been replaced some of the components like expansion tank tend to leak, I replaced mine,while I was in there put in a new thermostat,water pump,belts and Zerex coolant stuff like that and it was pretty straightforward,so nothing major at all
Great info here http://forums.bimmerforums.com/forum/index.php
Cheapest parts here http://www.fcpgroton.com/
DIY and your golden