They have a Sabre 30' you could charter here: SOUND SAILING CENTER - Long Island Sound's Premier Sailing School
out of Norwalk, CT.
It won't be cheap but will be cheaper then buying a boat.
Typical yearly costs for a <= 30' sailboat might be:
$1000+ winter storage
$500 or thereabouts for insurance
$100/year for NYS registration
Summer at a slip will be close to $3K, at a mooring maybe $1200.
These estimated costs are based on using a marina like a Brewers of which there are many on the LIS.
There are strategies that can bring these numbers down a bit.
Join a working sailing club. Examples of this kind of club are the Hempstead Harbor Club or Nyack Boat Club. You have to put some work time in to remain in good standing as a member but the yearly costs can be substantially less then using a marina. Neither of these clubs have slips so you'd have to buy a mooring (used ~ $500) and pay an initiation fee the 1st year. The down side to this kind of set up is that you can't launch or haul out whenever you choose.
The cheapest option is to go the no-club route where you pay someone to drop your mooring for you and pay a small yearly fee to the local village/municipality for the privilege. I paid a $25 resident mooring fee at a small harbor near Northport, LI where I kept a Lightning for a few years. It was also only a 50# mushroom anchor I could launch and haul myself. The Lightning lived on a trailer in the woods during winter.
Trailer sailors are always way cheaper to operate, but you already know that.