Make CD Versions of Public Domain Works
Repackaging public domain works could also take the form of CDs. Even if you are not particularly fond of this option, you will probably have to do this anyway as people will tend to look for physical products.
It has something to do with tangible stuff; people want to be able to touch the products that they buy.
Producing physical copies of your public domain products is not that difficult. Sure, it can be a hassle having to buy blank CDs and getting a CD-burning software to create CDs. But if you manage it well, you may even hire a separate company to do all this for you.
CD versions of public domain works are especially profitable if you are making revisions or updates on an existing product.
The picture above is one of my products. I hired someone off of Guru.com to read “The Power Of Your Subconscious Mind” by Dr. Joseph Murphy into a microphone turning it into an audio with a higher precived value.