This lady tried to recruit me to do such shows in the past. She was using just one of those $100 DVD karaoke players and a boom box. I didn't do it because I spent the money building my system, so I wanted to use it. It would have been overkill. It depends what you want to pay, like I said such show doesn't require much. I would try one of the sponsor sites, and click on their all-in-one section. Ace has a RSQ all in one for $350, the cheapest one I would call semi-home-pro. They have cheaper and more expensive. Check them or one of the other sponsors out.
Felix the KJ