Commercial isn't in the changing of money, but in the purpose of the image. If the purpose of the image is to entice people to an action that would, hopefully, lead to the exchange of goods or services, then the artwork is commercial and you are suppose to compensate the artist, or at least obtain the proper license for the project. So, in the case of the artwork for charity auction, then absolutely the purpose of placing the artwork in the auction is a call to exchange goods, the artwork for money. In the case of the Band posters, the call is to exchange money for the band's CD (which may or may not use the same artwork on the cover) or to attend a bands concert. In either case, the purpose of the artwork is commercial. If you have a peice of your artwork hanging in a building (which you gave for free or otherwise hung there, perhaps because you own the building) and it is there incidentally (or even intentionally) as "atmosphere" at an event where the event is commercial, but your artwork is incidental to the event, then your artwork is not commercial. However, if someone asks about the peice, recieves your name, and then requests a piece on commision, the work just became commercial. That's why you should use royalty free props as much as possible. Once you've gotten the rights to the peice, the issue is simply academic.