Perhaps because so few (if any) construction material suppliers in the Philippines do not do business online. There's a definite opportunity there. Another reason is that suppliers want their prices to be opaque, final prices are further determined by volume, they do not want their competitors to see their prices and lastly, supply and demand results in volatile prices.
For what it's worth, here's a list of prices we have. This may help you estimate your project. We recommend that you verify prices independently before moving forward. You also need to bear in mind that when it comes to finishing materials like toilet fixtures, faucets and even kitchen sinks, there is a high degree of variability in prices, depending on the look, material, finish, functionality and country of manufacture you ultimately decide to go with.
Please note some brands are indicated only to allow for verification and appreciation of the material prices. Green Homes Philippines is not endorsing any material supplier in the list below.
Miscellaneous Philippine Construction Materials as of September 2010
Prices in Philippine Pesos