I ended up buying the Golden Half, half-frame 35mm camera from SuperHeadz via the Four Corners Dark online store. A great little plastic toy camera with good engineering and build quality, Japanese made. It doesn't do square format, but one can always crop the resulting rectangular images.
Last roll of Ilford XP-2 I got back 53 prints, 4x6 sized.
I'm carrying a little flash along with it, for indoor shooting; a flash from an old Pocket Fujica 350 camera.
~Joe