This really depends on what you want to do while you are in the region. The refuges and campsites can be expensive so it is a good idea to join a group and share the costs. Take a good look at what is included in the price of your trip. On our Ultimate Patagonia trip we include accommodation in Buenos Aires at the start and end of your tour as well as domestic flights to Ushuaia and loads of other experiences such as boat trips, city tours, airport transfers and meals. These make this trip more expensive than the likes of our O and W Treks which are predominantly trekking trips. However we think the important thing is to look for value for money, not just the lowest price.
Our recommended guidance for spending budget per person on our Peaks of Patagonia and Ultimate Patagonia trips would be between $300-350 on top of your tips, whereas for our O and W Treks this is closer to $100-150.