What is your base set?
If you are on a budget, go with the Chartbuster E10 set (E9 too if you need 2008-2009 stuff). It has all of the major hits in all genres up to December 2009. Then, go ahead and purchase the Karaoke Kurrents ofr this year.
http://www.google.com/product_url?q=htt ... cQgwgwADgA
http://www.amazon.com/Karaoke-Kurrents- ... B003NZMCBY
That'll get you up to date on all of the major hits through about July 2010 for about $250.00.
Yes, you can get better quality if you want to go with the Soundchoice 2009-2010 discs, but it's gonna cost you more. Get your business up and going, then once you are making some $$$ reinvest it into SoundChoice discs!