I wrote a big long spiel and decided to delete it because I don't want to scare you LOL
When purchasing a used vehicle, you are always taking a risk. Have an independent mechanic check it out to make yourself feel better.
But 106k maintained miles on a 5.3 is good. These engines are tough! This works around to about 15,000 a year which is normal.
As far as price.. I'm not sure what the going price is in your area. Check around, use blue book.. and negotiate until you are comfortable.
As with any 4wd.. look for signs of abuse.