The phrase "sells on" refers to the popularity or reception of a product, idea, or concept among the public. The antonyms for "sells on" can vary depending on the context. For instance, if we're talking about a product, its antonyms could be "unpopular," "undesirable," or "rejected." In terms of ideas or concepts, the antonyms could be "discredited," "ignored," or "disregarded." If the subject matter is a person, the antonyms for "sells on" could be "hated," "ignored," or "unappealing." Using antonyms can help to convey more nuanced meaning and to provide a better understanding of the overall context.