FOLDER is available for purchase here and at the following stores:

192 Books in Chelsea, NYC.
Ada Books in Providence, RI.
Alley Cat Bookshop in San Francisco, CA.
Athenaeum Boekhandel in Amsterdam, Netherlands. 
Berl's Brooklyn Poetry Shop in Dumbo, Brooklyn.
Marfa Book Company in Marfa, TX.
McNally Jackson in Soho, NYC.
Mount Analogue in Seattle, WA.
Penn Book Center in Philadelphia, PA. 
Powell's City of Books in Portland, OR.