Sorry, been close to a decade since I've searched for supplies, but I bought my Silicon Carbide grit from a lapidary supplier operating from his home, he used to advertise in the Yellow Pages, called himself Western Lapidary or WA Lapidary Supplies, or something.
Bought some Aluminium Oxide from him but found it inconsistent(some larger grit in it causing streaks) but the SiC from him was excellent.
He also had Cerium Oxide but I never bought any(1/2 kg or 1kg bags from memory!), got some thru a club that's now defunct. Same club was a supply for polishing pads, an Optician's supplier would probably have them tho I've never inquired.
Polishing pitch (Gugolz) was bought at a store that sadly no longer exists, but it should be available form over east somewhere.
Sorry I couldn't be any more help, but will try tracking down the lapidary supplier for you.
Might still have his number here, but will need to dig through a decade of crap to find it.
EDIT: Blanks are available around the various astro-stores, but I bought a slab of 3/4" thick plate glass from Modern Glass(I think!
) and cut it out using a home made trepan.
but don't know anywhere over here that supplies mirror blanks, grit etc.
nup. Not enough people living here at the ends of the earth to support a local ATM supplier. I tried fixing that once (as MrB knows) but it didn't work out.
