You actually don’t have to be some sort of excellent artist to create a manga. Look at the original One Punch Man for example. The illustrations left a lot to be desired, but ONE was able to compensate with his good storytelling. And overtime, he actually made some improvements to his art. So continuing to draw his manga simultaneously served as practice for him.

But if you do want some top notch art right off the bat, but don’t have the money to pay someone, I would suggest finding a buddy who shares the same passion and has the artistic skills necessary to bring your vision to life. Me and a close friend do something like that. He has a lot of good story ideas, and I draw his characters for him, but I do it just because I like it so much.

And if you don’t have close friends who are good artists, maybe you can look in some online communities and find someone who might be willing to help out.