The white racks are powder coated steel. The arms are welded to the mounting plate. They are carried by Duluth Trading, Gempler's, and others.
Runs about $20 each. They are 20" long. A 12" long version is also available. Few bucks cheaper.
The racks are attached to the cross members with 1/4" x 1-1/2" truss head screws. 1/4" lag bolts can also be used.
The cross member is a couple pieces of 8/4 clear pine laminated (glued) and screwed together.
The end of the cross member is attached to a 1/4" reinforced steel angle brackets at each end with 1/2" carriage bolts.
The steel angle are attached to the wall framing.
The racks arms are welded to the mounting at a angle so weight on the arm just brings them down towards the horizon without the skis falling off. We can actually put 4 pairs of race skis on each arm - not so much with the wider boards.
BTW, the boot dryer is worth it's weight in gold. Save a lot of hassle with taking apart and reassembling ski boots everyday.