1) http://www.unep-photo.com/ (Prize: US$2000 for 14 under and US$5000 for 15 up) This is equivalent to about S$3400 and S$8500 respectively.
2) http://www.epson.com.sg/contest/index.html (Prize: Up to 3 million yen) 1 million yen is equivalent to about S$15750
For your interest...