Why are equipment racks so expensive?

Observing friends experience with Ikea racks deterred me from trying them for myself. I have no personal experience with these myself, but the prices seem reasonable.:
Furniture > Audio Racks (pangeaaudio.com)

It depends entirely of how you want to look at it, esthetically and functionally. You pay for the design, the thinking, the materials, the craftmanship. Audio racks purpose, apart from supporting and arranging, is to have the least possible sonic impact . 
DIY is fun and good results may be achieved, though for doing this it will not come so inexpensive as you think, and in the end the finishing point would be the starting of of well thought rack. Yes they are expensive but effective vibration control can start or end there. I do not regret getting my Bassocontinuo ones.

You don't have to break the bank to get something that is very good and affordable. Look no further than Butcher Block Acoustics for extremely well made racks that are relatively affordable.

Oz

It is child's play to make a very functional rack. Threaded rods with painted PVC pipe spacers and large maple butcher block cutting boards. You can even buy fancy feet for the bottom if you like. I would use casters. Makes the rack much easier to move. Cost? Maybe $500 at the most. 
I would much prefer spending the money on a new cartridge rather than a rack. Many of them are flimsy. The only equipment that needs isolation is the turntable.