It's hard to tell you how much of the air-ticket even the agency as its still a few months reach August. Raise the question in June or July.
Here I give you some idea....
HK--> Manila-->HK (Non Peak season)
Cepu Pacific ....around HK$1400 [tax193]
Phillipines Airline..around HK$1500 [tax193]
HK--> Manila
Cepu Pacific ... around HK$800 [ex tax]
The following roundtrip airticket prices (HK-->Manila-->HK) are extracted from www.ticketscentre.com website on 10th April 2004.
All fares are net, excluding applicable airport tax & security charge and subject to change.