I would echo Gemma's (hello Gemma and EcomCamp!) statements about the sadness it provokes in those of us who have seen the park suffer more than one serious burns at the hands of irresponsible travelers, while noting that it really doesn't take away from the overall scenic beauty of the park and your possible travels there.
It is hard to give a price range on the accommodation options, or to do so clearly, as most have programs where you're paying for lodging, as well as awesome adventures into the park with guiding, transport, meals, etc. During 'high season' or late Nov through March when the weather is best, expect to pay at least $250 a night at the lesser expensive places such as Hosteria Lago Grey and Hosteria Las Torres. It can almost save you money in the long run to do an inclusive type of experience at, say for example EcoCamp Patagonia or Tierra Patagonia. In terms of those 4 and 5 star lodges with great adventures, expect to pay between $1,500 and $3,500 for a 4 night 5 day program including your food, lodging, excursions, and transfers to from the park as well as entrance fees and permits.
Here is a short breakdown of some of the best lodging options such as I've described:
1) Explora - most expensive but incredible in every way, horseback riding in addition to other excursions - http://www.explora.com/explora-patagonia/.
2) Tierra Patagonia - Explora's new competition, little less expensive and awesome as well - http://www.tierrapatagonia.com/
3) EcoCamp Patagonia - great hiking-focused package that allows you to hike an abbreviated version of the famous 'W' while staying in comfortable accoms - much more affordable - Wildlife Safari option for a less hiking intensive itin also available - http://www.ecocamp.travel/
4) The Singular- very new and rave-worthy. Outside of the park but with access to park in addition to more fjords and vast wilderness outside the park. Horseback riding and kayaking excursions, excursions are generally a bit less 'active' - http://thesingular.com/puertobories
5) Patagonia Camp - middle of the group pricewise - really neat 'rustic luxury' concept where you're staying in really cool yurt style safari camp. Not as much flexibility in terms of excursions - http://www.patagoniacamp.com/index_eng.html
All my best in life's adventures,
Jordan Harvey - owner, Knowmad Adventures
"One of the best U.S. operators." - Frommer's, Chile