The most affordable and popular type of excursions in Turin is the panoramic tour. During 2-4 hours, a guide will take you to the most popular tourist spots (or drive you if you opt for a bus tour) - in one day, you'll be able to get a general impression of the city.
During the pre-Christmas period (from November 1st to December 20th), evening tours are very popular. The average cost of introductory tours in Turin is around 60 EUR per group, while individual tours start at a minimum of 100-120 EUR.
If you have the time, consider visiting the farms in Piedmont - the wine regions. Within these tours, you'll have the opportunity to descend into wine cellars, participate in tastings of different wine varieties, and purchase bottles at producer prices. An ideal route would be from Turin to Vercelli, Alba, and Novara, and then back. Expect to budget around 70-80 EUR per person per hour (average tour duration is 7-8 hours).