I would say "yes", as long as they matched song for song. It would definitely be a good sales approach for you. Are they SC cd's? Let us know how it goes because I have over 1600 dupes (including more than 150 SC) I am thinking about selling, and I too could provide matching files for.

...I have around 280 extra Original Manufacturer's CDGs that I'm thinking about selling. By law, can I include the matching ripped files (on discs, thumb drives, hard drive, etc.)? Thanks!

I can't answer your question as to all karaoke producers and publishers, because I don't know what their position is. There is at least the possibility, however remote, that you could be sued for distributing unlicensed copies of copyrighted works. To some people, there is a difference between making copies for your own convenience and selling thoe copies to someone else (even if the original media are included). You are taking a risk by transferring the digital versions.

For SC, while we would prefer that you not do that, we would treat those copies as though they were made by the person who possesses the original media. As long as they matched up in an audit, it would be all-square. If you are going to do it, I would recommend that you make it clear in your offer that the digital copies are tied to the discs and therefore can't be used on multiple systems.

I think that would be the only way you could sell already ripped files is when you supply the discs that match up with the drive. And as long as you do not continue to use said ripped files on your own.
Since their site is still down, they use to have a FAQ and one of the questions was could I make a copy of a cdg on video cassette/dvd so I can send to a friend with no cdg capability, the answer was yes as long as the original disc media was supplied with the video.
It wouldn't be any different with files I wouldn't think.