Do you have any examples of your colored pieces? Right now your ~$15 B&W sketch doesn't look great value for money considering the quality people on Fiverrr offer.
With that said, you should probably offer your services there, since you'll likely see far more interest there.
no example ... as this is a new service ... i will do it for 7 usd colored for you if you want to buy ...as you will be first customer ...pm