Wood hobbyists used these first for pressure treatment, so it’s not a marked up price for Cannabis use. This is a decent price. I bought my set up for less than $100.
Standard glass would shatter under these conditions. They are using acrylic or polycarbonate.
Don’t forget about the high pressure rated braided hose for tubing, the gasket for your top, the fittings that the tubes plug into, the Teflon tape (for best practices when attaching fittings), isolation (ball) valves, tee split, o-rings for sealing the tee split, and pressure gauge. You need them all to be successful.
It’s also best to have a filter on the air/pressure relief side valve enterance to ensure you not pull contamination into the chamber while releasing the top.