Todos Santos [1]’s two language schools charge about $120 per week for 4–5 hours of instruction per day plus homestay with a local family. Living conditions are very basic and most host families speak Mam, with a select few opportunities for homestay with Spanish-speaking families. Both schools also offer instruction in the local Mayan dialect.
The two schools are Academia Hispano Maya (opposite Hotelito Todos Santos, www.hispanomaya.org [2]) and Nuevo Amanecer (150 meters west of the plaza, escuela_linguistica [at] yahoo [dot] com).
Links:
[1] http://www.moon.com/destinations/guatemala/the-western-highlands/huehuetenango-frontier/todos-santos-cuchumatan
[2] http://www.hispanomaya.org