In 1982, on a visit to my parents's house in Kearney Nebraska, I walked into Gerbers Books & Gifts (the store just to the left of the World Theatre in this photo) and to my utter amazement found a brand-new copy of a reasonably hard-core-looking math book, Gerard Lallement's "Semigroups and Combinatorial Applications," for sale in the tiny books section, right next to the Garfield calendars, scented candles, and gift wrapping paper.
I bought it despite its astronomical price ($42), and spent a couple of months (that summer) reading it (pretty closely), eventually using what I learned to fake my way both to a PhD in Computer Science, and to scare up the misere quotient theory over twenty years later.