I'm almost up to 70k on my '07 (bought it at 30k) and haven't had any issues yet. At about 60k miles I had my diffs, transfer case, and transmission flushed and filled with synthetic. Other than that I follow the DIC oil life and try to keep it halfway clean. No issues!
I have a friend that just bought an '07 Avy with around 90k miles and he said it drives like a brand new truck.
What kind of deal are you getting? If it's cheap enough, then any mileage is acceptable! Haha....