We built one last year that was made out of the pvc type material. It is thicker but is very washable. If a customer vomits in one built with the nylon material it will be tough to clean and will shut it down for the night.
Ours was designed by me and the local canvas repair shop sewed it for us. They were really intrigued by it and did a great job with it. We gave them tickets to come through and really enjoyed going through their work.
The difference we did with ours is that it is in a "J" shape. Don't know of any that are in the config as ours. All I have heard about have been straight through, including one that is 40 feet long that I saw. It really freaks out the customers first to enter it, then to have to turn twice to get out. Many actually drop to their knees and crawl out.
As for the idea of paying the price, I know of many big houses that build nearly all their own effects without buying them.