There's no need to be famous, but it is indeed a plus point and an advantage to get more viewers,... I suggest to add Ads if they didn't have any, I have a friend that has a website and he's making money tru that but it wasn't that much, but I think it could help a bit. Or they could also ask some several casinos to advertise them in their site...
Also , I thought this thread are a list of sites that gives Casino Reviews, LoL.
Your suggestion is good and it would be helpful for the OP. But charging 50$ to add them on the site is useless. Because that will seem as they are listing by taking payment in this case reviews will have no value. And it will work as listing for payment, so users wont be able to know which is the best for them.