Congrats, first of all!
I'd include things that students would actually use & then fun stuff. Let me explain. I'd sell only the sparring gear they'd use in class/tournaments, uniforms, patches, etc. & I'd sell fun t-shirts w/ the school's logo on it. I wouldn't sell stretching machines & things like that that I wouldn't recommend (nor use) just to make a buck. If weapons aren't a part of your curiculum, don't sell it. I've always found it disingenuos when an instructor sells things aren't a part of their class. T-shirts, hats, gear bags, uniforms....all that stuff w/ the school logo is a great idea. IMO.