The problem with Cebu Pacific though is that if you have a foreign issued credit/debit card the website will not accept your card...it will be declined. There are huge threads on this on Lonely Planet's Thorn Tree and it has happened to me constantly over the last 6-8 months (trying 3 or 4 different cards!).
Oh and if you do manage to get your card accepted (sometimes there is a fluke and the card is accepted!) beware that Cebu Pacific don't change your flight time, cancel your flight or change the flight to a different day.
Last month I had the outgoing segment of my flight changed by 5 hours, the return segment was cancelled, then re-instated, then the time was changed and then finally was changed to 2 days later than the original flight date. It really messed up my onward flights!