sell someone on something

• Mary sold me on ordering pizza for dinner.
• John sold Anne on switching long-distance phone companies.
• An employee sold him on the notion that cable was the medium of the future.
• You know, I wasn't sold on this trip in the beginning.
• She tried to sell me the idea of buying my own paper shredder.
• She is hoping she can sell the idea to clients.

1. to convince someone to do something; to convince someone to accept an idea.
2. VERB | If you sell someone an idea or proposal, or sell someone on an idea, you convince them that it is a good one.

... McGraw-Hill Dictionary of American Idioms and Phrasal Verbs, Cobuild