An illustrator (or graphic artist, writer, fine artist, etc.) is an under-appreciated worker. An illustrator is a skilled worker, but often clients do not understand what "skilled" means. Here's a little story that might help:
Legend has it that Pablo Picasso was sketching in the park when a bold woman approached him.If she wanted an itemized bill, it could look something like this:
"It's you — Picasso, the great artist! Oh, you must sketch my portrait! I insist."
So Picasso agreed to sketch her. After studying her for a moment, he used a single pencil stroke to create her portrait. He handed the women his work of art.
"It's perfect!" she gushed. "You managed to capture my essence with one stroke, in one moment. Thank you! How much do I owe you?"
"Five thousand dollars," the artist replied.
"B-b-but, what?" the woman sputtered. "How could you want so much money for this picture? It only took you a second to draw it!"
To which Picasso responded, "Madame, it took me my entire life."
Drawing and materials: $1
Experience and knowledge: $4,999
The lesson here is one must not undersell their talent. Not only is it unfair to the artist, it's unfair to the whole industry you represent.