They are able to ask with a straight face because people will respond. Taking these jobs is just reinforcing the pattern. Stop helping these guys out and let them learn the folly of bringing an amatuer to do a professional job. So you don’t work that particular project; consider it an investment into the future when they realize their mistake and actually raise a budget for their next production.
Human nature, laziness, and supply and demand means these guys will always exist. It is your job to advance beyond them.