There was a really good article on this a couple weeks ago. Here's a link to discussion:
https://news.ycombinator.com/item?id=11183109
The answer to your question, sadly, is that you're not going to get much of anything by selling a SaaS business that brings in just a few hundred a month. Like on the order of a thousand dollars if you're really lucky.
Your options basically boil down to either shutting it down, letting it run neglected in the background, or stick with it and try to grow it into something better. Which you choose will have a lot to do with the state of the codebase, the amount of time and money it takes to keep it running, and what else you have going on that might be a better use of your time.
So in short, none of us are going to be much help. Good luck!