Good catch, Stephen! My two were gained in a similar manner - my first, a wooden boxed example, was something around a fiver posted, first and only bid. The other, the silver boxed E21, was practically given to me by a local chap who I bought some Gillettes from (eBay, but being local he delivered) and he brought a bunch of interesting things along.
But, boy, are they expensive now! Over a tenner for a tatty one and like thirty quid for presentable.
Good luck cleaning up - there are lots of moving parts on these, so be sure to move all the parts and let the cleaning phase do its thing. If you're using your ultrasonic bath, I'd say run it through, move the flapper, repeat and move it again ... repeat.
Okay, the blade - you have two choices, both of which need just a little snip. You can use a GEM, remove the spine and snip the corners off, or a Feather (not the DE blade
) ... one of these: http://www.connaughtshaving.com/fhs5.html ... again, the back corner might want snipping. If you do buy some Feathers, keep the spines from the GEMs and you can re-spine the Feathers to use in the 1912s.
I say snipping, it's more like snapping.
I used square nose pliers and simply snapped the corner off.
Also, now you find yourself with spineless GEMs and sharp Feathers, there's the Valet range which take them, too: http://www.theshavingroom.co.uk/forum/thread-23318.html ... in fact, you might say that the Feather blades are a direct rip-off of the Valet. I'm sketchy on the details, but gather there is a vintage Feather razor which looks very much like the Valet - perhaps they bought the rights, or just waited for patents to expire. Who knows. I have found pictures of vintage Feather razors will some very familiar designs.
I hope it's a good 'un. The roller at the front can crack, one of mine is, one isn't - rolling it down my face, it doesn't seem to interfere. I've yet to shave with it yet, though. You might well beat me to it. Enjoy ...