Best baking supply in Seattle?

What kind of equipment?

As a bakery owner in Forida, I know nothing about Seattle, but if you're talking about commercial equipment, and commercial quantities of flour, I doubt you'll find both in the same store in any town.

That sort of flour in warehoused and shipped, not sold over the counter.

OTOH, companies like U.S. Foods deliver flour and supplies for baking, and have catalogs of equipment that you can have delivered by them.

That combo is not normally found in Seattle or any city. Buy your equipment at Dick's on Fourth Ave So, just north of Spokane Viaduct or at Seattle Kitchen Supply in north Seattle on Aurora about 150th St.

Flour for breads can be found at many locations. I prefer either Whole Foods or Larry's.