Good luck. They seem to be hard to come by. For now your best bet is to keep an eye out in the cargo hold for someone selling some. MOW only has 12 and 12.5 available and those are the pre pros that have to be dyed.
You could always scratch build some in the meantime. I did some. It would be better than Converse. You wouldn't want to distract from the rest of your costume. It looks excellent.