Where can I attend a fight night club in Manhattan?

I have been thinking about a quick visit to New York in September/October, and I have heard about the 'fight clubs' inspired by, or reminiscent of, the 1999 eponymous film starring Brad Pitt.

Allegedly, these are night clubs with an improvised ring where random strangers pair off in a real-world fist fight where the last man (or woman) standing wins some money. Then it starts over again with a different pair of random strangers. I don't know about the legality of these establishments. I would like to be a spectator and can't imagine how that would be illegal (if so provide the statute where attendees can get in trouble). Anyway, laws change: At one point serving alcoholic beverages in NYC was illegal as were lap dance clubs and gay bars.

I saw an article in the Daily Mail (ok, granted it's not the best of British journalism) with some photos (but without specifics) leading me to think they are an authentic happening in NYC, hence this question. Happy with anything up to and including a USD 500 cover charge. I am not looking for a generic, NYC street fight scene, but a proper venue with table service and staff. The farthest out I'd be willing to go would be to Sheepshead Bay/Brighton Beach, or any place on the N Train.