For the first time ever while traveling SE Asia the room rates when you ask in person are half the price advertised on Agoda. If you are coming to visit phu quoc it's probably worth you switching to door knocking rather than pre booking you will save money.
On the beach bungalows to the south of long beach are around 40$ but if you go one street back and are not too bothered about direct beach access they are 25$
If you are looking on agoda/booking and it seems availability is low don't panic, the same happened yo us last week and when we asked in person there were plenty of bungalows available for half the price.
Mosquitos are HUGE here, pack your deet!