How to monetize SaaS?

I'm a college student and I've always found it a huge hassle to find a new apartment to live in. Student housing is not typically listed on apartment websites like rentler. There doesn't seem to be a solution for shared housing. At my university the only way to find available housing is to search facebook for apartment openings. It seems like there should be a better way to do this.

The road block I'm running into is how to monetize this idea. I don't think sellers would be willing to pay because they can list their apartments for free on facebook. I could charge the apartment buyer but I'm not sure what the best way of doing this would be.

Anyone have any thoughts on this?