You would be surprised at just how hard it is to find a store with physical stock of UPS batteries in the greater Seattle area. Batteries Plus in Tukila (South Center) is the place to go when your UPS dies. There are several other locations in Puget Sound as well. Everywhere else is a waste of time. In particular Staples is a waste of time.
Staples: I’m mad at Staples and am not going to shop there anymore despite it being the most convenient for me. It doesn’t matter what you call ahead about. Seems they always have it in stock. Until you arrive. And, then they can’t find it. “Would you like us to order one for you?” This is the second time they’ve pulled this crap. Same store, two different managers. Guess that’s shame on me but I’ve wised up.