It is $18 per campsite/ per night
Go to the DEC website and look for the link to Reserve America. They do the booking. Also be advised that most of the sites are either boat access only or accessed via foot trail. Only a few have direct car access.
I believe all sites are $18 a night or so last I checked for New York State residents. I believe it's slightly more for out-of-state visitors. You should be able to find the exact price on reserveamerica.com and search for forked lake NY
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