If you're looking for mileage since clearing DTC, even a $10 Chinese Elm 327 will do. For such simple things, software is more important. For example, I use a program called Piston along with the cheap $10 scanners to look for such things along with simple codes.
When buying a used car from a private party, especially a German or high end car.....scratch that, these days, ANY car, odometer rollback is probably the most important.
Having a tool that can tap into all the modules that store mileage is critical. Carly does that, especially on German cats.
Even a $100+ is a worthy investment when car buying.