I was watching Paul in the Philippines and he was talking about his near meltdown in Saigon airport returning to Manila. The counter lady checked his ticket which he bought onwardticket.com for 12USD. Which is a rent a ticket that cancels in 48 hours. Well he didn't read the fine print and it canceled since he bought it 3 days earlier. Anyways long story short after a few more pathetic attempts he buys another throwaway and when it's verified by the airline employee at counter, it works.
Basically if you go to any onward ticket site, there's more than one. You can get a valid onward rent a ticket that cancels 48 later for around 10USD. Just make sure you buy it about a 24 hours before your departure to the Philippine to satisfy Customs requirement.