Keep in mind when you add a laser to your CNC machine you also need to add an enclosure and add additional safety interlocks to avoid damaging your eyes or an observer's eyes or skin. The laser is a fantastic device and many are extremely powerful. There are rules about selling lasers, that is probably why you will find it difficult to find exactly what you need. Most of the Chinese lasers are cheaper than just some of the parts for American made lasers. Reading on the zone most people seem to think the Thunderlaser company from China has machines that seem to work and don't breakdown right away. Probably the most common compliant on Chinese laser machines on the Zone is they stopped working. The laser no longer fires or the machine stopped moving. Some people use laser diodes for engraving, but CO2 laser is much more involved with mirrors, lenses, etc. This would probably be a pretty good investment unless you have a good business model to make some money. Best of luck to you.
Russ