I imagine most users are engineers employed by companies. This would tend to decrease the price sensitivity while increasing the desire to go with a brand name.

I see now McMaster-Carr has their own knockoff, they for sure can successfully leverage their reach, reputation and brand recognition to compete. I imagine price must go down once enough people catch on that this is a relatively unprotected commodity and enough reputable players have cross compatible offerings.

https://www.mcmaster.com/products/t-slotted-extrusions