150k miles or kilometers?
What does "branded non" mean? Clear title?
I took a look at a USDM E39 M5 here.
The seller supplied Carfax was clean.
The Carproof, I ran myself, showed that it had been salvaged in NY state less than 3 weeks before importation into Canada. The car was exported before the title was officially tagged salvage in NY state and thus entered Canada as a clear title car.
If I had ONLY relied on the Carfax, I might have been the proud owner of somebody else's piece of junk
If you follow the instructions on this thread,
you can run an Autocheck on it yourself.
I'd use all of those checks if possible however the recommendation is to analyze their results before the purchase of the car.
If it's an 2003 150K miles car in pristine cosmetic and mechanical condition, I'd say it could fetch up to 19K USD on the high side. This would be with lots of receipts and tons of maintenance history...a perfect high mileage example with lots of wear and tear items proactively taken care of or at least taken care of on a schedule.
If it has hood+trunk+roof+door dings with missing badges/spoiler/interior trim and requires a replacement and/or repaint of some parts then that certainly devalues it by at least the amount of the parts, materials and the labour.
Unfortunately, if was cosmetically neglected, one might surmise that it was neglected mechanically too.