Well, those don't look too hard, at least the basic stuff. You can probably find a turtleneck that will work for the one with the long hair, and the kimono top is pretty easy to make. Their basically just rectangles sewn together, and you can also find patterns at sewing stores. If you don't have a machine, you could hand sew it, though that would take longer. Basically, I recommend a lot of Goodwill trips, and you might be able to find the pants and stuff without having to make them.
The mask might be a bit tricky, but there's this stuff that's kind of like papermache, but more bandage-y, and you can make masks with it fairly easily. I remember doing it way back in grade school, but also more recently. Don't remember what its called, but I know any craft store should have it.
Hope this was a bit helpful. Good luck!
