an option that has worked for me is to fly a domestic airline to either LAX or SFO, then buy a ticket from either LAX/SFO to MNL on cathaypacific's website (which tends to be cheaper than discount websites). I saved over $200 this way when compared with the the exact route through one ticket

The downside is you will have to pick up your bags and recheck in LAX/SFO if you checked in your bags.