Building Maple stand need inexpensive wood supplier

If it’s beauty you’re after get only grade AAA white maple. Oh, and you’ll pay for it. But an inexpensive alternative is Baltic birch ply, a rather handsome wood, actually.

We have a great place here in Michigan that supplies a wide variety of woods. I was able to order some very thick quartersawn oak for the tops of my Sound Anchor amplifier stands.

I think it is all about how you conduct your internet search.  I looked for places that supply woodworkers assuming they are likely to know where to source wood.  I looked around just a couple of minutes on the web and have included a link below that might help.  With a few phone calls, you may be able to find somewhere that can source what you are looking for.  Just glancing over the list, I suggest you start with Frost Hardwood in San Diego.
https://www.google.com/search?q=woodworking%20supplies%20san%20diego%20ca&rlz=1C1GGGE_enUS488US488&oq=woodworker+supplies+san+diego+ca&aqs=chrome..69i57j0.13006j0j7&sourceid=chrome&ie=UTF-8&npsic=0&rflfq=1&rlha=0&rllag=32822368,-117173388,6610&tbm=lcl&rldimm=11970610243811531332&ved=0ahUKEwi5kKz1_rrZAhVD21MKHaKUBbcQvS4IcDAC&rldoc=1&tbs=lrf:!2m1!1e2!2m1!1e3!3sIAE,lf:1,lf_ui:10#rlfi=hd:;si:11970610243811531332;mv:!1m3!1d307230.5848711836!2d-117.112376!3d32.855669549999995!2m3!1f0!2f0!3f0!3m2!1i129!2i275!4f13.1;tbs:lrf:!2m1!1e2!2m1!1e3!3sIAE,lf:1,lf_ui:10

Thank you all. Mitch2 you read minds. I have a request in to Frost, though even 30 years ago there were no bargains to be had there. Ultra high quality however, is their watchword. 

Geoffkait,

With a nod to your missives re spring loaded mass, I was thinking of hanging the maple shelves on springs below the level of the outer metal frame , rather than placing them on top of the frames with sorbothane bumpers. Your thoughts please. 

Akg_ca

just scoped out Mapleshade.  Their prices are the reason I want to do it myself. Absolutely beautiful work. I hope I can get near their craftsmanship.