Do you guys have a recommendation for a good but cheap auto chromatic tuner? I'm trying to he my kid "hear" when he's out of tune, and I'm thinking a tuner maybe one way to train his ear. He's into gadgets like most boys his age so it should make it fun for him. I want an auto chromatic model, i.e. a model that automatically detects the closest note, tells you what it is, and how far off you are. Easy to read display, common battery type (not the watch batteries) and/or AC adpater would be good too.