For what project did you buy 210 rubber domes?
I am a materials person (not "material") and in model making I am always on the look out for stuff I can either use for kit bashing or for textural elements. I also do a bunch of massing models for theme parks and other architectural environments. And simple repetitive geometric objects can make my life easier much of the time and a bit interesting (in an ironic way). I am also a sculptor and I will be using many of the keyboard components for that as well.
I am currently not buying them, although I was going to go that route as I can get large lots of keyboards off Ebay. The prices may be high initially but in relative terms very worth it! (but the lack of mechanical keyboards and the lack of variety steered me clear) I am currently getting them donated from multiple anonymous sources. I would say some or many dont work, but I have no way of testing a majority of them.
I have taken apart over 200 of them so far but I must say there is enough of a variety to keep things really interesting!
I have seen really interesting switches, rubber domes, membranes, metal plates, keycaps, springs, screws, circuit boards, leds, smells, and lint! Enough to make you sick and happy all at the same time =P