A piece in the Times entitled "Their House to Yours, via the Trash" talks about how book scavengers eke out a living on New York's mean (main?) streets.  The target of their hockery: the Strand Bookstore, a Mecca for booklovers and booksellers alike.

Most of the stuff they sell ends up in the $1 bin outside the shop, but that's actually one of the first places I end up looking on a warm day, and the treasures you can find there are startling.  I once blundered across an original copy of Mel Lyman's Mirror at the End of the Road in that bin, although when I found out a bit more about Lyman I felt weird having it around the house and got rid of it.