I have wondered the same for manhattan, but I imagine the available plots are very few there. When I looked it up in manhattan though, if you could get a plot, the cost was only like $25/year.

i'm a member of a community garden in bed stuy. far from home but it was the closest place where i could actually get a private bed.

at this point i'd say good luck, plots everywhere have been snatched up like mad. guess a lot of people are forseeing a big rise in food prices and suddenly vegetable gardening is in again.

to get a plot you'd want to find gardens near you and talk to the main contact. you can track that info down through greenthumbnyc.org. most beds are in the $20 area, and you of course have to work at the garden from time to time.