One way or another, you'll be screwed. However, i found that once a currency leaves its natural domicile it becomes, in a perverse way, more valuable when you need to acquire some. In order to offload it, money changers (as opposed to banks and companies like Travelex) will generally offer a most attractive rate. The guys in a hole in the wall in Singapore will give you a far better rate than you'll get at any bank. Have you thought of them?