Quick answer: New York City runs about EUR 250 per day mid-range - noticeably less if you eat local and walk. Cheapest window: April-June and September-early November - mild temperatures and long daylight; December is festive but cold and crowded.
What things actually cost
subway ride (OMNY tap)
2.70 EUR
pizza slice
3.50 EUR
flat white at a cafe
5 EUR
pint of beer at a bar
8 EUR
Broadway rush or lottery ticket
40 EUR
mid-range hotel double per night
220 EUR
Eat well for little
Pastrami on rye at Katz's Delicatessen - enormous and worth it once, about 24 EUR
Classic slice at Joe's Pizza in Greenwich Village - the benchmark New York slice, about 3.50 EUR
Bagel with lox and cream cheese at Russ & Daughters - about 14 EUR
Soup dumplings in Chinatown at Joe's Shanghai - about 10 EUR a basket
Halal cart chicken over rice near 53rd and 6th - the late-night classic, about 10 EUR
Money mistakes to avoid
Booking a hotel on Times Square for the 'real New York' - you pay a premium to sleep in the most touristy block of the city
Paying 40+ EUR for a Statue of Liberty cruise when the Staten Island Ferry passes her for free
Taking a taxi from JFK by default - the AirTrain plus subway costs about 10 EUR versus a 65 EUR flat-rate cab
Buying full-price Broadway tickets - use the TKTS booth, digital lotteries or rush tickets and pay half or less
Transport without the tourist tax
From JFK take the AirTrain plus subway for about 10 EUR, or a flat-rate taxi around 65 EUR; from Newark use the AirTrain plus NJ Transit for about 15 EUR. In the city just tap a contactless card or phone on the subway - rides are about 2.70 EUR and it runs 24 hours.