Following are the places:
1) NSP, Pritampura: It has a lot of places to offer, be it Billu's Hut, hastag foods, and much more at a reasonable rate.
2) Connaught place: Places like Wengers, MacD, Dominos, variety of street foods, some other small restaurants and shops, offers quality food at reasonable rate, as eating doesn't need to involve lots of money.
Satya niketan: There are lots of cafes where you can go and enjoy a hearty meal without actually getting broke and the total bill would cost around Rs.800-1000 depending on cafes.
3) Majnu ka Tilla: This place will be a gem if you want a great day with your friend.
4) chandni chowk: You can explore lots of street food over here at a reasonable price and feel satisfied.
These are some of the good recommendations to try.