I've been looking forever and can't find one. I would order it from Tilly's but I'm a little nervous about the price tag and the sizing. I've bought stuff from Tilly's before and never had much luck with figuring out their sizing.
If there is a Forever 21 near you, I would stop in there. F21 seems to always have a little bit of EVERYTHING, and it seems like they should carry a heathered gray open cardigan