If you have landed in La Guardia Airport (LGA) and want to take public transportation to NYC, you either need exact change for the MTA bus (US$2.50 as of 2011), or a MetroCard with enough money for a one way fare.
Don’t have enough change for the bus? No need to scramble or buy unnecessary stuff at the airport…there is an MTA vending machine at the arrival level of LGA’s Terminal B. The MTA vending machine accepts credit cards and is located in between the United and Continental’s arrivals baggage claim area. See map below for more details:
If your flight doesn’t land at Terminal B, no need to worry as LGA has a free shuttle bus that circles around the terminals. Another option is look for a newsstand called Hudson News as they may resell MetroCards. You should also consider the unlimited ride Metrocard if you are staying in NYC for longer than a week. Here’s a previous post regarding on how to take advantage of NYC MTA’s unlimited Metrocard.
From LGA, visitors can ride the M60 bus to Upper West Side Manhattan. Buses and subways are both run by the MTA, so transferring from a bus, to another bus, or to the subway is free - as long as that transfer occurs within two hours after the initial fare was paid. If you paid the bus fare with exact change, you’ll need a transfer pass; you can request one from the bus operator before you exit. If you paid the bus fare by purchasing and using a MetroCard, it’ll automatically act as a transfer pass if used within the two hour window. Here’s a link to Captain G’s previous post for more details.
And if you’re arriving from John F. Kennedy International Airport (JFK), you won’t run into issues finding a MetroCard vendor or transferring. There are tons of MTA vending machines at the JFK AirTrain, which takes riders from JFK to the Jamaica subway and train station, making it very convenient to go anywhere in New York City. For your convenience, here are links on how to get from JFK to Manhattan (How to take NYC public transportation to/from JFK).