Let's get things clear. Disc duplication is NOT about making unlicensed copies of software or movies for sale or rental. This is a business that will require some investment in terms of CD writers and software. Your clients will basically require you to make copies of their corporate presentations, training videos or recordings of their events to be distributed to their branches or to customers. Your business would mainly cater to small and medium sized companies who do not have sufficient volume to go to the big CD manufacturers.
This business would be a logical extension of a Media Conversion Service, except your primary responsibility would be the duplication of CDs. Some clients may require up to a hundred copies, some may require thousands – especially if it's promotional material. Depending on the size and services of your business, you could include doing the artwork as well as packaging for the discs. Bear in mind though, you will need to screen the content of the CDs you are duplicating. You do not want to unwittingly duplicate illegal material. A good side income for the technically inclined Audio Visual type person.