Thank you for using JustAnswer it is my pleasure to assist you.
Collectors of this type of art are generally interested in well known names you also need to have provenance such as a letter from the artist stating that they painted the piece, where they were when painted, such as where they were incarcerated, and date painted.
This is a very small pool of collectors and not many known auction houses or galleries will sell this type of art so you will have to sell it through an online venue such as eBay.
Please let me know if you have additional questions on your art. I am here to fully respond to you question based on information provided to me.
Thank you, Michelle