Book fairs
This kind of fair attracts mostly school age, high school age and college age cause, books can be bought in cheaper prices than in book stores. This is a targeted audience, the fair is still opened to all of the visitors, no matter what age they are.
For a couple of years, you can even find books for a dollar or less just, they are usable, which isn't that important considering the low price.
I've visited this fair every year (pavilions 5 and 6) since my high school days just, this year, I'm kind of fed up and, my book collection is pretty complete.
I like travelling book fairs as well, where I don't have to travel 3 hours to Zagreb. These fairs were near me last year, where older books and their older hardcovers could be find. More or less at cheap prices. Books, you've got to love them :)
The picture's link:
https://www.google.com/search?q=interliber&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiika-hoY3eAhXF1iwKHXwyCMYQ_AUIDigB&biw=1366&bih=657#imgrc=tqAlZg6YECmMdM: