You have to take the wheel bearings apart to do the ball joints anyway. Might as well have them do it at the same time.
As far as keeping cars a ton of miles I feel it depends on how much work you can and are able to do on you own. Paying a shop $60+ an hour in labor can add up fast and make it not cost effective to keep older cars.
We own 3 vehicles. 2004 Chevy Silverado with 205k miles, 93 ranger with 196k miles, and an 84 Cj7 with 200+k miles on it. I do pretty much all the work on them so it is cheaper for me to work on them then what a new car payment would be.
My dad is still rocking a 1999 Ford Escort with 335k miles on it. He tried to sell it running a few weeks ago and the best he could get was $250. He decided to keep it and drive it till it dies on the side of the road some where.
