I love used photo books
It is rare there a new photo book that catches my eye - they all seem to scream 'digital this...' or 'photoshop secrets that...' these days.
My local symphony has a used book sale fundraiser project that accepts donations of books year round, and warehouses them at a mall that still is a worthwhile neighbourhood mall, but is past its glory of retail days (one department store has been converted to an an insurance company). One week a year , usually a few weeks after the kids are back in school, there is a sidewalk sale type of affair. The final day you can buy a large bag for $5, and fill it with whatever books you can get in it. We usually go early for the good stuff, and on the last day for a winter's worth of novels to read.