304 East 48th Street, New York, NY
The package is 14 dollars from anytime between 1:00pm and 8:00pm. If you are the earliest you can just post what room you are in and start singing, people will join you as they come in. There is no minimum for rooms and you pay the 14 dollars in the beginning so switching rooms and leaving rooms early is also easy.
The bar is half price all day and there are many delivery menus to order food from.
You can also look some of the songs up on Duet 48's website: http://www.karaokeduet.com/songs.html
These are not all the songs they have though. If you don't find your song here it might still be in the system some where.