There are many way to enjoy Quebec City without spending a lot of money. Most of the suggestions here cost nothing at all.
For starters, Quebec City offers a three day museums pass that includes 20 museums and attractions plus two days of public transportation.
Walk along the UNESCO-designated wall that surrounds the old city.
Grab a walking tour map from the tourist office. Walk the brand new, well-signed, VivaCite Stroll that takes in some interesting landmarks.
Attend a free, open air concert on the Plains of Abraham.
Visit the Museum of Fine Arts on free Wednesdays.
Ride the ferry to Levis for great views of Quebec City.
Take in the numerous street festivals and carnivals.
Lunch on the tasty hot dogs at the take out place on Rue St. Jacques (look for the sidewalk sandwich board) in the Saint Roch district of Lower Town.
Check out the free traditional Quebecois music (boite a chansons) at the upper level bar, Chez son Pere, just off the main street, Rue St. Jean.
Pick up some new Quebecois designer wear at great prices at Simon's Department Store on Rue St. Jean. Simon's has been a Quebec institution for over 100 years.
Sample local cheeses, fruit wines and tapenades at the Farmer's Market in Lower Town.