On the trek to basecamp we stay in rustic teahouses at the organizers expense, so you do not have to pay. Here is some text from the Island Peak itinerary page :
Trek to Basecamp:
4) Walk to Namche Bazaar (3,450 metres/11,300 feet). Teahouse.
5) Rest and acclimatization in Namche. Teahouse.
6) Walk to Pangboche (3,750 metres/12,300 feet). Teahouse.
7) Walk to Pheriche (4,250 metres/13,900 feet). Visit the Himalayan Rescue Association health clinic. Teahouse.
8) Walk to Dugla (4,600 metres/15,100 feet). Teahouse.