Dining in Iqaluit is limited and expensive — everything is flown in, and prices reflect that. A simple lunch can easily cost $25–30. Come prepared, and don't expect variety.
The hotel restaurants are the most reliable. The Granite Room at Discovery Lodge Hotel is the most established, serving standard Canadian fare at hotel prices. Túnngasugit (the visitor centre) sometimes has locally inspired food events.
If you get the chance to try Arctic char, take it — it's the best cold-water fish you'll eat, and the char from the rivers and lakes around Iqaluit is excellent. Caribou (usually as a stew or roast) and maktaaq (raw beluga whale skin and blubber) are traditional foods that are sometimes available at community events. Do not expect these on a restaurant menu, but if you're invited to share a meal with a local family, accept enthusiastically.
The grocery store (NorthMart) is expensive but has the basics. Prices for fresh produce and anything perishable are roughly three times what they are in southern Canada.