I'm trying desparately to find a pair of Chinese "Mary Jane" type
shoes/slippers in white.  These shoes are typically canvas, with a
thin plastic or rubber sole.  I can find black, red, burgundy, and
even once an off-white linen, but never white.  I would need to be
able to purchase a single pair, as I am a customer, not a wholesaler.

breanne, 
It is obvious you have already done an exhaustive search....you
already found everything I was able to come up with. Perhaps the
slippers on this site could be a the next best thing? I also checked
the online versions of Target, Old Navy and M-mart. Try

http://www.ldcreations.com/women/shoesslippers.html

There are several styles on this site, none of which match your
request, but they are WHITE! The Mary Janes are not flats, and the
flats are not really Mary Janes, but have a look.

Heres hoping someone can find them.

Not quite right, but a very interesting place to look!

I actually found them on my own, kind of by mistake!
http://www.lotus-eaters.com/maryjanes/mary17.html
in case anyone else wants them...