Just to keep things straight; Copyright does not care whether or not money changes hands. If I xerox copies of the latest Harry Potter novel and give them away on a street corner I am still guilty of copyright theft. Trademark does care, but only in that a trademark is a business asset that was developed at some cost and needs to be protected against adulteration. Lucas Films, for instance, would be entirely within their rights to shut down anyone using the trademarked shapes of Tie Fighters or the trademarked term "Jedi." They chose not to, reasoning that their property is not harmed by use within the fan community. However, if they let a feature film use these elements they'd risk losing them entirely, allowing a new film company to take over and profit on the work Lucas did. So don't look at the money. Look at the morality, and look at the explicit permissions. When in doubt, check -- most major companies, for instance, have a list of their trademarks somewhere on their websites, as well as a statement of policy concerning them.