I guess it depends on where you live, but generally speaking, you could try a charity store or the Salvation Army store. Sometimes, there are buildings well-known to have many of such stores. In Singapore, Bras Basah Complex behind the National Library has many such store. You could also try online at your local ebay(cheap shipping), or Amazon.com if you’re in the USA. In amazon.com for example, a sixth edition Campbell & Reece biology textbook in good condition costs $15, while a new seventh edition one costs over $120. (Although the price seems rather steep…my international edition purchased new cost me S$70, which is about US$45) There usually isn’t much difference between editions, and in this case, I have the latest edition, and have seen the other, so I know what I’m talking about.

if you live in our country (Philippines), Recto is the place……there’s less than or more than a hundred “peso” (currency) textbooks.

I can answer this but the place is in my country…….

You can ask it in your country……………

www.academicbookservices.com

this should help you.