Prices for branded/imported items are considerably more than the USA - as they reflect (excessive) Philippines import duties and costing in an noncompetitive local market. However, some companies do make/sell 'local copies' of certain items which are more reasonably priced.
For the Makati area:
Nautilus on Arnaiz, in Makati, are an OMS stockist - and have a great selection of the 'little stuff' (boltsnaps, cave line, etc). A veritable Aladin's cave of useful nik-naks. Their website isn't up to much in regards to listing the wide variety of stuff they actually sell. Solomon (the owner) is a charm and really helpful.
Aquamundo, nr Mile Long, in Makati, make their own stuff - a cheap option if you need a BP&W, regulator, wetsuit etc. Quality is good, staff are friendly and knowledgeable.
Aquaventure Whitetip, stocks DiveRite, Apeks, Suunto etc. Average prices for the area, but very helpful staff. They are probably the biggest importer/distributor of scuba products in the Philippines.
ScubaWorld stocks Aqualung, Pelican, TUSA and Suunto, amongst other stuff. Friendly and good for general scuba kit.
Dive Central, Mile Long, in Makati, sells a range of stuff, including DSS. Pretty expensive. On previous visits, I found their 'on-duty' staff didn't have much scuba or product knowledge though.
Adventure Bound sells Halcyon. Expensive, but specialist. They are GUE focused.
Adventure Bound distributes the Halcyon Equipment
Adventure Bound (Adventure Bound)
Unit LG 2 Alfaro Place
146 L.P. Leviste St. Salcedo Village
Makati City 1227
Tel. No. 840-5523
look for Alex Floro
Or get in touch with Martin Lorenzo (GUE instructor) 09209107137