Where in the PI are you going? If you are only going for P4P or do you have other items on your agenda. As stated above there are lots of bars and what bars are good tend to change and the quality of girls can vary by the hour. One thing to remember is unlike Toronto the girls in the PI are very open to older men so in if you are good with opening a conversation you can talk to and pick up waitresses and girls from all over and end up at your hotel just by paying for the night,
Manila is the most expensive AC (Angeles city) is a cheaper option with lots of girly bars
Cebu gives you a nice beach town with girls (lesser than AC)
So there are many options I would stay away from agencies as for less you can get girls that will stay with you the whole night and even for days if you want. If you are looking for a new girl every night make sure to let the girls know your a butterfly so they are more likely not to flock to you the next night if you go to the same bar.