be sold on something

be sold on (something)

To be confident in or convinced about something's viability, veracity, etc., often to the point of being enthusiastically supportive of it. I don't know, this plan still sounds pretty risky to me—I'm not sold on it yet. After seeing the presentation, I'm sold on this investment—let's do it!
See also: on, sold

be ˈsold on something

(informal) be very enthusiastic about something: We were really sold on the idea.
See also: on, sold, something