Once again I was on the hunt for a used bookstore, in Krakow this time. I finally finished the massive seventh (and final) book in my series that I obtained way back in Australia, and was ready to lighten my pack further.
I found a really useful website, called the Bookstore Guide, that lists many used bookstores throughout Europe. In Krakow there was listed a place called 'Massolit Books and Cafe.' I headed over there one day, and found an awesome place with many rooms of books, and a cafe to boot! I was able to sell my book for 12 złote, and my pack has much more room.
I'm down to one book now, and I think that one should last me until I get home!