Coloured Graduation Gowns

We've had the go ahead for next year's school performance, going with Fame, and one of my initial tasks is to source (either bought or hired, whichevers cheaper) 100 grad gowns of differing colours. My first thoughts were find some cheap white mass produced ones and dye them, but all the white ones I can find are either Poly, and there for un-dyable, or are silly money. Unsure the exact figure at present but its almost non-existant. Just curious as to what other ideas may be open to us, or if any one in the UK has done the show recently and has the robes we could hire (shows not until November) or can pass me a company name, I'd appriciate it

Check with the school administrator. They probably have a source of gowns for the real high school grad.

They are pricey if I recall, I remember spending in excess of $30 for mine 13-14 years ago, but that might also be the mortarboard. I think it's still hanging up at my mom's house somewhere, which leads me to my thought- following May (at least in the US, not sure about UK) there are no shortage of 18-year-olds with robes they've worn once and will never wear again. I wonder if you could arrange a collection of slightly used graduation robes?

Churches also have choir robes, which might do. If you call a few locals they may each be willing to loan a few of their color.

Or on that same note- (I call them altar servers) have white or black robes too..

Instead of gowns, since they seem to be so pricey, we have opted for all the cast chipping in a few quid (since our budget is "can you beg, borrow and steal this please?) for mortar boards, found several different variations of and ordered some samples.