I've had meals in Manila that cost about $6 too. It really depends on how adventurous you are. BTW, if you're into Italian-American food, Manila has much better pasta and pizza than HK does. They even have Sbarro's out there, which really made my day. You definitely want to try some Pinoy food out there though.
If you're going to have all your meals at the hotel, expect to pay HK prices.