Fair use is tricky because whether the use of copyrighted material is a fair one or not is determined by a COURT, this after the copyright holder has decided your use of the material is infringing on their rights and decides to sue.
It is always wisest, therefore, to get permission from the copyright holder FIRST, before using any copyrighted material (regardless of how fair YOU may think your use is). Getting permission first is what the Copyright Office recommends, and what I would recommend, as well.
That said, you can generally use the image of copyrighted material to sell that material, if you are using the material in a descriptive way only.
For instance, I can sell my (legally purchased and owned) copy of Christopher Moore's novel "The Lust Lizard of Melancholy Cove" by showing the cover of the book and describing its content - although if I quote portions of the book, I may be in legal hot water. I can sell my (legally purchased and owned) copy of Eminem's "Recovery" by showing the cover of the CD but I could be infringing on the copyright if I provide a sample of one or more of the recordings. And, I can sell my (legally purchased and owned) DVD of "The Book of Eli" by showing the cover of the DVD, but I cannot show a film clip from the DVD without risking an infringement suit.
How much copyrighted material is too much to use, in other words, and whether your use is a fair one or not, would be a question for the courts. If in doubt as to whether your intended use would be considered a "fair use," it is best to show an IP attorney in your area what, exactly, your intended use is, or seek permission for your use from the copyright owner.