[playersare]

bus is cheapest, but you cannot go directly from Port Authority to Borgata (their poker room is where the bus depot should be, ironically). go to gate 81 and see if any buses go to nearby Harrah's or Trump Marina. otherwise, take the first bus available to any boardwalk location, and then cab or jitney to the borg. including the cashback coupons, round trip should be well under $20, with service leaving Manhattan every 30-60 minutes.

bus drawbacks - no reserved seats so sometimes it's a bitch to get back to NYC if the waiting line is long. make sure you bring a friend, or lots to read and/or listen to during the trip so you don't have to deal with all the weirdos riding with you.

renting a car is very convenient but it's hard to find something under $60 a day in NYC, if not $100 a day, plus gas. depends on your budget.

there is no direct NYC - AC train service. you basically have to go from Penn Station to Philly first, then turn back towards New Jersey. I would pick option #1 or #2 instead.