Copyright, Licences, Public Domain
It’s acceptable to charge for cost recovery (which could include cost of printing + basic overhead), but bookstores cannot make a profit on the sale of an NC-licensed work. Think of it like this: What does the bookstore need to charge to break even—and not make a profit—when it sells a printed copy of the NC-licensed textbook? Those charges would be acceptable.
Cost recovery (printing cost of the book + basic overhead) is widely accepted as allowable with NC-licensed content.