We used to buy or rent used college books at Recto when we consider saving a few pesos that could be used for our other needs. The improvised bookstores in that place offer the best deals as the books are sold at the lowest prices.
As the phrase implies, used college books are those secondhand books, nearly new or old, that still serve as references or resources for college subjects, school reports and projects, and position papers.
In the US, there are established stores for these kinds of books sold for students whereas in the Philippines, some of these small stores are makeshift ones, found in nooks or corners and usually along the university belt.
Recently, online stores in the Philippines now offer these used books that could be bought or rented at cheaper prices.