Has anyone done such a sales option/mod for doing this?

What I want to do is offer the "buy 3 CDs and get the 4th free" and have the customer choose from the 6 CDs available.

Not sure of the best way to do this.

Any suggestions?

blip

There is a mod that does this, although I don't see it listed on either the cubecart.org site nor the cubecartforums.org site.

Try a Google search for