Still a
reliable surplus vendor, incidentally:
http://www.cadigital.com/
Perhaps the best-known NOS selection of 8" floppy drives anywhere in the
world, as well as 8" media and cleaning kits.
Some of the prices don't
look like they have been updated in a decade
though, 2 MB ram simms for $59 etc.
With most surplus vendors, I've had very good luck with bargaining
on items having obviously outdated posted prices. But make a reasonable
offer, not a really lowball one, or they'll not bother to talk to you.