If just an F717 and a few filters I guess a small airtight container (tupperware or big dumex or milo tin also can) with some silica gel will do.
If still want to buy electric dry box, then Carrfour is the best place for the DRI-CABI .
Singapore definitely must have dry box. Don't bother with those tricks from places like states or UK where the weather is very different, they are are either cold and wet, or hot and dry, both situations fungus cannot grow. Even if their weather do get humid sometimes, the duration is usually short, so not too bad. some of the tricks like your UV light method may work in those countries. In Singapore we have a rotten climate, everything rots here.
I recently got hold of a box of cameras and lenses from a relative who didn't bother with keeping dry. Oh what a heartache it was to see all those equipment going to waste!!
:cry: