There are certainly Kaya spreads sold in Asian supermarkets in N. America, but the taste can differ. In Singapore, 'Ya Kun', 'Killiney' are famous coffee shop chains that sells their own Kaya toast bottled for tourists. Personally, I have bought them as gifts for family before on checked-in luggage and I believe SingPost could offer shipping overseas. The taste differs quite a bit from those found in the Asian grocery stores so give it a try at their coffee shops while in Singapore first to see if you like them.