No, I don’t see that it makes sense, particularly for an alternator, but I also don’t see the sense of storing brake pads and air filters.
I’m assuming you live in civilization somewhere and drive a somewhat reasonably common car. If your house is 40 miles down a gravel road from the nearest running water and electricity and you’re driving a 1989 Sterling I can see having a store of spare parts. But alternators and brake pads are available at any auto parts store. They’re not a week away.
By having all those things stored away you lose the buying power of those dollars, and they’re not easily liquidated, if they are at all. Instead put that money in a mutual fund or take a vacation. When you die you may regret that trip to Hawaii you never took. You’ll probably not remember that alternator in the closet.