Seems like a pretty good way of finding out an upper limit to a sustainable logo sales business. Increase prices until people stop buying, relaunch with logos a bit below that cost.
This is a promotion to make people excited about the logos that this guy creates. The pricing of the individual logos is irrelevant outside of the promotional value they give to the designer.
Adding some tension like this increases perceived value, and watching other people take logos due to the raising price makes the perceived value go up even more.