I won't even bother to name all the usual brands.. how come a hifi shop needs to ask them? Other than getting free advertising here. ;-)
Anyway, how about Hifiman? It's becoming pretty popular and acclaimed.
We even got distribution now here far away in Finland and the prices are almost the same as US$ which is surprising. So it suggests the distribution chain is good (or our local one is selling them dirt cheap with no profit).
I don't know what it usually takes to be an "authorized seller", but how hard can it be to offer all popular brands? Even the small stores here can sell you pretty much anything (never mind the price).