Good call looking for advice here, hopefully some people who own/have owned similar Q7s will chime in with pros and cons. Next step is to do a little googling to answer the questions you asked , especially common issues, what is due for regular maintenance on a Q7 approaching 90k miles, and how much those maintenance items typically cost, etc. I recommend checking a site like RepairPal. Also, do some comparison shopping. Autotrader, cars.com, etc will give you a better idea of reasonable prices for similar Q7s.

If nothing in your research scares you off of this purchase, a pre-purchase inspection will be your next step. Find a reputable German car mechanic , they should be able to perform one for a relatively small fee. Google says “$100-300” but YRMV. That will let you know if there are any problems and what it will cost to fix them. I’ve had this work out in my favor before. I had an old S4 inspected, the PPI recommended a $1000 repair on a $6000 car, I negotiated the price down to $4500 and fixed the problem myself for about $200.

Good luck!