They're lovely, those GEM Super Stainless aren't they? Funny, though, I was chatting to a pal in the States who seems to be able to get those quite readily and he rates them about as dangerous a plastic crayon that couldn't cut its way out of a paper bag! Oddball
Okay ...
GEM/Personna are going to be your staple.
PAL & Treet can be had from various places online - these will have 009RD on the spine. PAL, I think, are carbon steel and will appear to rust as you use them.
Oh, GEM Blue Star as well ... and CVS, both of which seem to be found in US Pharmacies.
Occasionally, you'll find a cost-effective method of picking up something like GEM Super Stainless.
NOS GEM & Ever Ready can be found every now and again.
DO NOT think about using window scrapers - these are two facet or single facet blades and just not sharp enough for shaving. Shaving blades are three faceted.
Don't forget, you can take the spine off a GEM and slip a Feather into it to use in your 1912s and Micromatics.
Choices are limited, but I think that's no bad thing really.
Hoosier Trooper wrote a super guide for us over on TOST: http://theoriginalsafetytoo.proboards.com/thread/98/single-edge-blade-guide
... and if you snip the edges off a DE blade and slip one edge behind the blade lugs, snap the lid closed on a 1912, it works. Quite well, actually, but a bit of blade chatter.