Hawaii

Honolulu, Hilo, Pearl City

Honolulu:
Pacific Store Planning (website)
     (just store fixtures, no gondola)

I want to give a link to this local classified ad platform, they might get occasionally
Used Hawaii (website)

Make sure you check craigslist, Facebook Marketplace or "offerup",  and any other LOCAL classified ads.
The only people who sell fixtures in Hawaii (on the web) don't sell gondola, new or used.

There are also dealers in Seattle, Oregon, and California.

There are west coast dealers who will serve you.

Honestly, you WILL have a tough time finding USED store shelving in Hawaii (the Alaskans are laughing at you).