I put about 85 miles a day on my van. I guess that would work out to about 4,000-5,000 miles on these tires. I do tend to wear out my front tires faster because it's a newspaper route vehicle, but it's usually pretty even wear across the tread.
The distance from the tire place to the alignment shop is about 10 miles, if it were an extreme distance of 100 miles or more, I would just get the tires at the alignment place. They just charge much more for installation and then charge extra for rotation and again for balancing every 5,000 miles. Works out to about $30 each time, which over the life of the tires is more than enough to buy a new set. I can keep the old tires to take to the alignment shop so they can see what was wrong and then give them the state tire disposal fee to dump them.
As for how long I plan to keep this 'gem' of a vehicle, the engine and transmission are actually newer with only about 40,000 miles on each so I intend to keep it until one of them quits. Replacing suspension parts every now and then (or most other parts for that matter) still works out to less than what a monthly car payment would be.