I agree on Mogami's availability via the typical distribution channels. I note that Guitar Center prices their prebuilt mic and guitar cables on the high side compared to their own brand names.
I've had the pleasure of working with Mogami signal level cable when I was working at Universal Audio, the recording gear manufacturer. All of their internal wiring is all-Mogami. They make up all their own harnesses with it.
Now that I'm no longer there, I miss picking up the scraps. This past week, I looked around the Internet trying to find a seller who would sell less than a complete roll of the cable. I was looking for internal wiring stuff and not speaker cable. Outside of Michael Percy, there are few places that even mention they have it.
For speaker cable, though, I'm still ok with the Home Depot 14 gauge extension cord.
Cheers,
David