Bought a couple of books on abebooks.com after an email from a friend with some recommendations. I bought the following:
A Theology of Liberation: History, Politics and Salvation by Gustavo Gutiérrez
A Common Faith by John Dewey
On the Pragmatics of Social Interaction: Preliminary Studies in the Theory of Communicative Action by Jürgen Habermas
Communication and the Evolution of Society by Jürgen Habermas
Faith on the Edge: Religion and Marginalized Existence by Leonardo Boff
Theory and Practice by Jürgen Habermas
I also found a Paulo Freire biography by James Kyrilo from 2011, apparently a good read for joining critical theory and liberation theology. Got it shipped to Harvard Book Store, so free shipping.