I bought my niece's Lamaze cloth book a year ago in SM Department Store - kids section. The big department stores and toy stores have stocks of it. Estimated price range would be from Php 300 - Php 500. If you prefer cheaper ones, I suggest you go to Divisoria. They have a variety of cloth books too.
There are cloth books available at Baby Company in SM, Toys R Us in Robinson's, and other stalls with baby stuff like the stalls at Greenbelt 5.