In short
Puerto Natales is only of interest as a base: it is the last town before Torres del Paine, two hours away by road, and the only place in the region to hire gear and buy supplies.
The park is the most visited in Chile, with two classic routes: the W in four to five days, the O circuit in eight to nine.
What it really costs
Chilean Patagonia is expensive: everything comes up from the north by road, and the season lasts only four months. Supplies bought here cost noticeably more than in Punta Arenas.
The park has its own entry fee, and refuges and campsites are paid separately. A full W staying in refuges runs to several hundred euros on top of transport.
What nobody tells you
Refuge and campsite bookings inside the park are compulsory and in your name: without them, entry to the circuits is refused. They open months ahead and fill fast.
Three different operators run the park's accommodation, each with its own site. That is the point that sinks the most last-minute plans.
The Patagonian wind regularly passes a hundred kilometres an hour in summer. It is not an occasional nuisance: it dictates walking hours and kit.