The cost difference can get more dramatic than just the more expensive materials - its like painting the mural 2-3 times plus no changes can be made once its painted. Definitely not for the average client. However it gives the great advantage while marketing yourself as an artist.

People love fresco for the authenticity, the glory, and unachievable in any other media depth of the pure colour and feel, etc., etc.

For the beginner its best to start with the small panels, this way exhibitions and demonstrations can be made, as well as panel can be sold as an individual piece or used as an example to show to the potential client the difference in the feel and touch between the real fresco and the mural (acrylic or whatever).