I read media digitally, but for my kids, this was great.
Re-stocked daily, children's books $1.
A lot of the younger children's large books have the plastic covers on them you can remove when you get home, same hardcover underneath often in excellent condition.
Check your local library, I'm sure many cities have these sales.

Picked up 20 books for $20, some of them retail for $20 each, new.