Supply and sourcing are curious animals. I'm reminded of this every time I go to Ikea to buy $30 "Stolmens" to get 14 feet of that beautiful anodized aluminum tube for projects that would cost me more than $100 to buy raw from my local metal place.
Well, IKEA probably buys 14,0...0 feet of aluminum tube a year, and their volume allows them to take lower margins than your local metal place, so it makes perfect sense, really.