[@Dinh AaronMk]
That really sucks :/ 
Not being paid is one of the reasons I'm afraid to take commissions. No matter the art, we pour our hearts and souls into our work, and then more often than not, the requestor bails.  Now I'm not familiar with your medium, but as for myself with my knit and crochet work, it's easier on me to make something and then sell it. It's probably what I'll stick to. If I did a commission, I'd probably ask for 75-100% up front to check their seriousness. 

I really hope your requestor gets back to you and pays you.