You've got me, I just picked them up at a local Menards home improvement store. I'm sure Home Depot or Lowes might have the same brackets. All they are is an L shaped shelf bracket made of very heavy gauge steel. The plastic cover just snaps on to the back, covering the metal and making it look more presentable if you used them for shelves.

If I recall, they made 2-3 sizes.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85