Chandni Chowk is going to win your heart with all the great options they have for both shopping and food!
For shopping go to sarojni nagar and for food GTB nagar in delhi
For shopping, head to Sarojini and for cheap food, go to Chandni Chowk
Karol Bagh has a lot of shopping options along with delish food option like Roshan Di Kulfi and more
Sarojini and Lajpat markets, Janpath too are the cheapest markets where you can find stuff from varying qualities. These have options for street foods as well as good cafes/restaurants nearby