I need a chain drive: a ~3 inch cog driving a ~6 inch cog, with 7 or 8
inches in between them. I would only need one set.

I got curious about using the silent Ramsey-style chain but cannot find
anywhere that retails the chains and the cogs.

Ramsey being a brand-name of the drive chain that looks like this-
http://www.ramseychain.com/index.asp

I don't need to use Ramsey in particular, I'd just want to buy the same
brand of chain & cogs, since they aren't guaranteed to be perfectly
compatible across manufacturers.

There is lots of different companies that make this stuff, but nobody
seems to retail it at all that I could find in a couple hours of looking
online. I get a few places in the USA that make it, a whole bunch of
places in China and India that make it, and people selling replacement
motorcycle transmission drive chains on eBay.

I have looked for variations of "silent drive chain", "inverted link
chain", "metal belt drive chain" and so on, and got nothing.

Is there anyplace online a regular person can actually buy this stuff?