I don't know the Bangkok place you mention, but if you want to bargain head to Quiapo. Not the best part of town though, so I wouldn't be dragging around carry-ons there. But if you've been to BKK I am guessing you have some experience.

Mall of Asia is easy to get to and more "westernized", not a bad choice either but not so much of a bargaining place IM(possibly outdated)O.

You also might have enough time to do the Corregidor tour if you're so inclined. My favorite thing to do in Manila by far, but not sure what time the boats leave in the a.m.