Seattle, Tacoma, Spokane, Vancouver WA

Washington resources:

Renton:
Mr. Racks (website)
(racking and shelving)

Monroe:
Continental Store Fixtures (website)
(new and used)

Kenmore:
James G Murphy Auctions (website)
(Auctioneer)

Puyallup:
American Retail Supply (website)
(new only)



Check craigslist (website) for store fixture liquidations in Seattle, Spokane, Tacoma and other local regions, even out of state.
If you can't get shelving in Washington, your shipping/delivery costs will sharply rise beyond Portland, OR.

Washington State can be a difficult place to purchase large, bulky retail store fixtures and shelves.

If you search the web for 'used shelving in washington'...half your results are from Baltimore.  I'll assume residents of Washington are used to this.

Nestled in the northwest corner of the United States, it doesn't provide a good shipping point from anywhere, though it might have more options than you realize.
The first order of business is to seek out a closing grocery or dollar store for used retail shelving; decide now if you will settle for an off-brand, as it may open some doors for you.  If you are in a peripheral city, like Spokane or Vancouver, you will first want to check major cities and shipping points.

Seattle is the first place you should seek out used gondola shelving, even if you live in Spokane.  Smaller towns and cities simply won't have the retail activity nessecary to, likely, fill your stores needs.

Start by searching Seattle for store fixture liquidations; extend this search to nearby major cities, like portland and Boise.  The first thing you want to avoid is shipping a great distance, and shipping through the Rocky Mountains.  Searching Northern California might become nessecary if there are no applicable closeout sales running in Washington.

Be sure to check the local dealers, too.  Again, it might be tough to find your exact specifications from a local gondola shelving dealer, but you might get lucky, and they will have exactly what you need, in stock.

Also, you will find a major dealer in Portland, just across the border.
Try these nearby states:

Oregon

California

Canada (our newest state!)

Utah

Arizona