Please help, advice would be greatly appreciated.

the best way is

determine how long the project will take From Start to Finish (your best quess) - include all time needed - aka actual making and preparation and travel

calculate what will be fare compensation for that time:
there is no formula or standart rate, especially at the beginning, so just pick the number that would make you satisfied.

calculate the materials and other expences

add those two numbers and add 15% for "unexpected"

you got the price...

learn fresco at http://FrescoSchool.org

fresco painting video tutorials: http://www.FrescoSchool.com

also visit

Fresco School Video Channel
http://youtube.com/FrescoSchool

Contemporary Fresco Gazette
http://trueFresco.Org
commission fresco or mural http://iLAdesigns.com

Here is how I would go about pricing artwork. First ask yourself how much your time is worth. How much do you want to earn? Once you've answered these questions, you should worry no more.

You do not need a degree in art to create art. As long as you have the desire to achieve your goals and the skills in order to meet them, then you are all set! Good luck with your next project!

Muralist~ D. Windseth