I guess with many things, they are easy to get if you know where.
Ordering online one can find 8x10 easy enough, but as of this morning, after calling our friends in Oxnard, I found they are out of their film roll and will not be restocking 100/125 speed film.
JandCphoto.com however, has a nice stock of all these film sizes and except for a somewhat soft emulsion, perform very well.
They would have to come to Singapore via the US from Eastern Europe.
Hope that helps.