A cross pendant/pin/earring/and so on? Any Christian store will have them, and I think HotTopic has some, too. Definitely check HotTopic for the stuff you don't think you can find anywhere else. I got my red jeans there, just when I was losing hope on finding any. xD
And then, of course, there is always the option of stopping by a Michael's or any craft store and just getting bakeable clay if the jewellery is too expensive. Bakeable clay is like...$3.00 or something, maybe cheaper. And any of you probably have safety pins laying around somewhere, so it makes a quick pin. :3
...Hey, Naruchan, were you at the photoshoot? If so, which Russia were you?