Yes your software is open source, and most likely it is downloadable for free over the Internet, but that is no reason why you shouldn't sell it too. Maybe that doesn't make sense to you? With Damn Small Linux we sell it on CDs and USBs. We are a small group, so we do not offer a custom label, but we do offer small hockey ring shaped business card CDs with DSL pre-installed. You may want to sell a nice labeled CD with your software. You may be surprised by how many CDs you end up selling.
We also sell bootable USB pen drives, and that has been a very good seller despite having very easy to use USB install scripts in DSL. Many other software packages could be useful on a USB drive besides bootable operating systems.