coconut milk powder
It's much more common then you think. They have it at every large supermarket you just have to know where to look for it.
IGA, Metro and the likes will have the packets (i cannot remember the name of the brand, the one that is everywhere with Asian something...) which have oil and paste mixes for various asian dishes. There is a blue packet for coconut powder.
Otherwise, you can go to any asian market and they will have it cheaper.