I'd be very interested in 30g domes and keycaps of all sorts.
However, like others have said, I'm not sure if this would be financially beneficial for yourself. For example, say I wanted 66g domes for my HHKB. That would require the domes from 60%~ of a full size Realforce. I'd probably pay reasonably less money than what the Realforce board would cost (or else I'd just get one myself). This leaves you with half a board, until someone opts to buy more 55g domes from you, but that would require you to purchase another board, and then you'd have two gutted boards, etc etc
Maybe consider something like trading your domes for the member's domes, along with a service fee for yourself. I dunno bruh..