This is an interesting dilemma.

I don't have good advice necessarily, but I'll tell you our thought process.

First, we wanted good cosmetics. We also wanted as good as possible mechanicals. We do DIIY a lot of stuff (some stuff we don't), so we were stuck between the following 2 options:
- go cheap (<5k), and fix. Mileage anywhere from 130-200.
- go higher price (8-9k), and hope there are no near-term repairs. Mileage up to around 130ish.

Keep in mind, we were only looking at 3.0's.

We looked at plenty. Ones with alleged good mechanicals seemed to have dents or crapped up interior, and vice versa.

After looking at probably 12-15 cars, we decided to go option A. We went a few higher miles than we wanted, but decided to give this a shot.

The main reasoning was that, even with our prior X5 (which we owned since it was CPO at 40k miles), stuff wore out all the time. BMW's "lifetime" parts are 100,000 mile parts. So, there will be lots to replace after 100k miles. It's annoying, and why people probably talk used BMW's down, but in a way, it's to be expected on a vehicle like this.

At 100k miles, expect to replace the whole coolant system: radiator, all hoses, water pump, thermostat, expansion tank. Probably $300-400 DIY, almost $1k dealer.

Soon thereafter, from control arm bushings, and drive shaft boots or axles. Again, cheap DIY, expensive elsewhere.

Also at around 100k miles, expect valve cover gasket, and oil filter housing. The former is around $250 and the latter $700 for someone else to do, maybe $100 DIY.

Alternator and battery may go as well - another $500, more if someone else installs.

Honestly, if I was not a DIY person, I would check maintenance history as closely as possible, and find one with as much of the above already completed as recently as possible.

We chose Option A above so that we could have a few thousand dollars to use for whatever comes up. In our case, we had very little maintenance history, and we have paid for it to catch up from the prior owner.

Maintenance records were sketchy for many of the cars we saw. I did see one that had the axles and control arms done, but no word on coolant system and oil leaks.

We figured that there was a fair chance that we'd be doing all of this anyways, so we might as well go cheap and have some money left to do it with.