Hey, Lito! Nice to hear from another Filipino modeler! I know what it's like to be on a tight budget, so i know what you mean about cheap kits - be warned how ever: a lot of people here have trouble explaining to wives/parents about the number of unbuilt kits they have! Like shermie said, what is it you're interested in?
Dwight and Allan have mentioned most of the shops already, but there's also "Special Toys" in Virra Mall, Rustan's Cubao and SM North Edsa.
Oh, and this is for all the Filipino modelers out there: Natalie said that she can order stuff for you from abroad, for as long as it's from http://www.hannants.co.uk !! (It's kinda dangerous, really...) Oh and allan, she says Hi.