Thought Provoking - Thoughts Needed

I have been toying with a few ideas in my head, but am unsure of how to work them into reality. At some point last week, I went to pick up a freecycle posting for paint. The woman said that they had gallons of paint (some brand new, some half full, some nearly empty) up for grabs. I grabbed them in hopes for using them for a mural in the basement. I sent her a couple of photos of Teo's room just for fun and she said that people would pay lots of money for paintings like that.

I have thought about it before, offering to do murals and such, for a small amount of pocket money, but wouldn't have a clue what to charge or how to go about doing anything like that.

Then, yesterday, my mom said that a coworker of hers wanted to know what I would charge for a drawing that she could frame and hang in her nursery of a jungle theme. I don't have a clue what to charge! I would love to do it, but do not know what those would be worth. Basically, she wants a colored pencil drawing approx. 10 x 12 inches. My mom showed her photos of Teo's bedroom and of a drawing I made my mom for Christmas one year.

So, what should I do? Should I try to market my art, either as murals or framed art to match up a room? How does one do that? How much would you pay for personalized art and/or a mural?