There is a good Money changer at "The Arcade" 2nd floor callded People's Corner. Always a lot of people queueing to change $$$. Infact there are a few there. This one seem to be the better one.
The rate for most currencies are not bad.. Can call them some more to find out the rate. But rate is ever changing, it's too violatile..
People's Corner (Nearest MRT Station is Raffles)
#02-07 The Arcade
6223 3040
Happy changing...