The easiest way to get around New York City (Manhattan) is on the Subway and The fare for subway or local bus rides is $2.25*. While the fare for an express bus ride is $5.50 and a SingleRide ticket is $2.50. You can also buy a Pay-Per-Ride prepaid MetroCard which allows you to buy as many rides as you want from $4.50 to $80.

Unlimited Travel
If you are in New York for a longer period of time or looking to do a fair bit of travel there are a number of unlimited travel options for a fixed price.
7 Day Unlimited Ride MetroCard
30 Day Unlimited Ride MetroCard
7 Day Express Bus Plus MetroCard

Unlimited Travel (Airport Train)
JFK-AirTrain 10-Trip MetroCard
JFK-AirTrain 30-Day Unlimited Ride MetroCard