Selling into the US we have C-Quest, ORA, ProAquatix (Currently in a major move and off line), TMC, a few larger Asian ones, a big one up and coming in Thialand and medium sized ones scatterred across the US. I'd say collectively there's probably around ~300+ smaller breeders selling locally.
There's two breeders in SoCal that cover most of the lower LA region and San Diego region with their stock, one being Seahorse Aquatics.
There's a site dedicated to marine breeders, www.marinebreeder.org if your really interested in finding more information
To my knowledge they are, and always have been, US based. They're owned by a larger food fish aquaculture company of which is one of my customers They simply moving to another US location. I don't recall where.
Seamaiden, nice to hear from you again, been a while ProAquatix is the one your talking about, but both C-Quest and ORA do gobies and blennies. C-Quest has quite a long list now, and a graet new website to boot