Grab four roommates and listen up: there's a five-bedroom duplex up for rent in Alphabet City for only $5,500 a month. Do the math, and that's a bargain $1,100 per person per month to live on Manhattan Island. (Yeah, you're almost in the river, but details, details.) EV Grieve, who first spotted the listing, called it "charming," which is one word to describe an apartment where a mattress sits on the floor without a frame. Perhaps "Urban Dorm Room" would be more apropos? Nevertheless, the hammock in a lush, somewhat overgrown backyardclearly photographed months agodoes score points, as does the in-unit washer/dryer. Recent grads, get ready to fire up the barbecue.