There is a lot to do that is free in NYC especially in the summer. Lots of outdoor festivals, concerts in the park, Shakespeare beyond the well-known Shakespeare in the Park. MOMA is free on Friday nights and it comes with a long slow moving line to get in, the Met is open till 9 PM Friday and Saturday night and is pay what you want all the time, the NY Historical Society is pay what you want on Friday, same with the Morgan library on Madison and 36th St, the Jewish Museum is free on Saturdays and so on… and if you need to go shopping, Lord & Taylor, Macy’s and Bloomies are generally open till 9. The Duane Reade drug stores are frequently open 24 hours. There are lots of inexpensive Thai restaurants and pizza places and coffee shops all around.