I've found quite a variation in Manhattan from free to no BYOB at all. Here is a list of some NYC restaurants and their corkage fees and policies:
http://nycorked.wikispaces.com/
And see:
http://nymag.com/restaurants/article.../winechart.htm
And this author states that $35 is probably the average for NYC:
When is a high corkage fee really worth paying? What could you get for $250 that you couldn’t for, say, $25? That’s the average cost of corkage nationwide (it’s about $10 more in New York City).
http://www.foodandwine.com/articles/...nefits-of-byob