Here is a good story of someone who bought a 4Runner with 329,000 miles off of E-Bay, last month. He flew up North and drove it back down to Florida. If you go on the E-Bay link, it doesn't look bad.
Having driven some good cars till they die, I would say it cost about 2 1/2 more in maintenance for the second 100,000 miles, than the first 100,000. After 200,000 miles it gets to the point on how much the SUV is worth versus the repairs.