Canva + pixabay
Pixabay has free art that is not as great as custom drawn anime, but that’s something.
Overall, if you are writing a novel, it doesn’t have to be an anime. Just look for an image with a human face or male abs, position it well, make sure it’s not too busy, and add title.
Most of the books you see in popular, with anime cover are actually novels that are made by the comic book writers themselves, so they didn’t have to commission their covers.
As a writer you do not need to be fleeced for cover. There are a lot of popular books that have Canva covers, even their free templates that are used for tons of books.