I wish ya alot of luck.. good equipment that does not require a Audio system, will cost a bundle.. now if you have the audio gear, and the people that can run them in a flash, that is simple. Players usually start at around $300.00 USD from many places then there is the cost of the Karaoke media.. CD+G's & DVD's they can run from anywhere from $32.00 USD on down to I have seen them as low as $12.00 and still be singable. Depending again on where you purchased them and thier quality. Mail order Places can advertize lower prices Yes it's true and sometimes are a great value, the downer is the Single CDG/DVD or low volume orders are the kick in the butt.
They cost more sometimes in shipping than the gas to go across town and wait a week to get it in at another place, or wait til you or your group can order a bunch of them at once.
Been there myself many times.
My suggestion is to get a "CD+G" player as I can see these things not going anywhere for a while, and the media is not either. As the media is available everywhere from Walmart to E-bay to links here on KS.
Personally, I'd try and shop around for a 3 tray JVC or RSQ 33 series, IF not the RSQ 505 is another good one to try, and that does DVD Karaoke.
I have both of them.
Best of luck to you.