BMW dealer won't be buying them from auction at that mileage, the thread title mentions auctions so not presuming what's meant.

Have you researched the vehicles fully, at that mileage cars with the recommended service histories are getting close to timing chain problems in more than enough cases to be concerned, careful selection required, the wise private buyers are servicing their cars at shorter intervals but the majority bought via companies won't be.

not cheap..have replaced a few myself...upwards of 8 hrs for certain engine derivatives.

add a couple of hundred quid for a decent chain kit...oil change etc... that cheap forecourt bmw bargain doesn't look such a good deal does it lol

I had a BMW 320D and did 150K without issue or timing belt.

In general dealers look for a max mileage of around 60-80k tops