Some of the most pleasant options for budget backpackers include hostels managed by friendly Argentinian families who live in the same space. Try Pehuenia (URL: www.hospedajepehuenia.unlugar.com/) in El Bolson, where the owners cook up the most affordable asado you'll likely find on your entire trip ($3-5 including wine), or Casa Verde (URL: www.casaverdehostel.com.ar) in Trevelin.
Outdoor enthusiasts will find that there are plenty of low-cost (and often free) campgrounds in the Lake District. For a more exciting option, there are many Refugios in the mountains that offer camping or lodging for reasonable rates, and many of them offer their own artisan beers as well. Be sure to bring your own camping gear with you as prices are higher here than they are in Buenos Aires, and in general, outdoor gear is not cheap in Argentina.
The Lake District is known for its large offering of beautiful and quaint cabanas, which can range from budget to upscale options and usually include great views. Hotel Llao Llao (http://llaollao.com) is the most famous and exclusive resort in the area. The resort rests between two lakes beneath the mountains just outside of Bariloche, and rooms start at $385.
Other Hotel pages in The Lake District that may be of interest: Bariloche Hotels, Esquel Hotels, Lago Traful Hotels, Zapala Hotels, Parque Nacional LanÃn & The Pehuenia Circuit Hotels, San MartÃn de Los Andes Hotels, Villa La Angostura Hotels, El Bolson Hotels, JunÃn De Los Andes Hotels and El Huecu Hotels.