This PCS, we unloaded a lot of stuff that we won't need for this tour: the second fridge, the second car, vacuum cleaner, washer and dryer, lawn mower. Great for moving, and most of it was at or near the end of its useful life anyway, but not so great when we eventually go back to the US and have to replace it all at once. There's only one sensible thing to do: prepare. Make a list of everything we'll need to replace, guestimate how much it will cost, and start saving a little bit every month until we go back. Since I have no idea how much these things will cost, whether we'll find used or have to buy new, and when this need will actually arise, there will be quite a bit of guessing involved. So here goes:
Washer and dryer: $1000
Vacuum cleaner: $150
Lawn mower: $200
Second fridge: $800
for a grand total of $2150. Of course there will be other expenses, but I can't anticipate them now and I shouldn't procrastinate beginning my savings. We've got 34 months left on these orders, so 2150/34 comes out to approximately $65 per month. That doesn't seem totally unmanageable.
For me, the next hard part is separating that money from our regular funds. You can open a dedicated account at one of the banks you are already using, or you can figure out another system that works for you.
I promise, if you implement this plan every time you move, you will be delighted when the next move rolls around and you are not scrambling to pay for expenses that you knew were coming.