I usually buy older cars that have been well taken care of and trade them in or sell them before repair costs get too high. When do you trade in your cars?
I usually trade my old cars in before the miles get too high. Usually it's around 80,000 miles. I never want to hit 100,000 because I hear that's when everything start failing.
If I want to upgrade to something better, then I will usually do it with my old car as a trade in. I usually buy certified used vehicles from a dealer. It has always worked out well for me.