Regarding mileage, getting something above the 100k mark is risky. Past that point, there's a good chance that very expensive things start breaking. However, since cars past that point tend to be cheap, you can probably repair 2 or 3 such parts before the repair cost would exceed the cost of a newer or lower mileage car...maybe. We have a truck that's well past the 100,000 miles, and its only had a handful of breakdowns over its life, and only 1 post-100k. If a car is reliable enough, getting a high mileage model might be worth the risk. Just don't try to drive it on any long road trips, least you wind up in the middle of west virgin with a dying transmission, unable to use the reverse gear or stop driving for fear of being unable to get going again (unless you like being able to empathize with the cast of Speed).
"There's suspension of disbelief and then there's insulting my fucking intelligence"