The school do very well from what I can see, although I think thats likely because they are a good school. There are requirements for certain gear. Things like gum shields n mitts for sparring. Also particular other things for competitions. There are regular competitions. Good results from the practitioners. These things are not pressured, I could probs find cheaper alternatives on ebay although it would take a bit of time and effort searching, ordering, sending back if its wrong size etc.
I think there is a fundamental difference between schools in the UK and elsewhere. Most of the venues are places like high school/college gyms, social clubs, MA centres and places like that. If there is a charge then I cant imagine it being a great deal like buying a whole store or something. There is a big turn out for most of the evenings I attend. I imagine that there is a good deal of money passing through their hands, although I dont begrudge them having it.