Advice needed - Facebook page appraisal

I just remembered I'm an editor on a facebook page related to movies (general movie niche) with 18,000+ likes. I'm thinking of contacting the owner to give me admin rights so I can try and monetize on it. Bear in mind that the last 3 posts on the page are over a year old, and the rest are from 2014, but the page keeps growing on its own (50+ new likes p/m, and 150+ page views p/m).
Since I have no idea how much the page is worth as-is, I'm asking for a helping hand to give me a rough number on what it might be worth so I have a number if the admin refuses to just leave it to me.
P.S. If any of you could benefit from this page and the traffic let me know, I'll gladly help if I manage to take ownership.
Also, any ideas or advice on monetizing is welcomed