This is a sort of corollary to your question - it's a table I made up from reading 'round threads about long-term ownership and what maintenance you should do that's not on the standard BMW service schedule:
https://www.2addicts.com/forums/show...php?p=27767885
So basically, the higher the mileage the more things you'd want the previous owner to have done on top of the standard BMW service schedule. For some of these, if the owner hasn't done them and the car has survived, then they'd be things you'd want to schedule asap after you take ownership yourself. For others - like more regular oil changes - you may give preference to cars offered with evidence of such.
The big items worth spending money on seem to be a more robust replacement charge pipe @35-40K miles, and getting a certified specialist ZF outfit to replace the auto oil @50-60K miles (almost no BMW dealers have the equipment, and tend to say the oil is 'lifetime'). See the table for more detail.