A little expansion on your response, based on our experiences:
None of the programs we went through paid the hosts. It's usually on a volunteer, cultural experience basis.
Hosts are expected to feed the student, provide a bed (some programs require a private room), assistance in transport to/from school and extracurriculars.
Hosts are encouraged to pay for the student's portion of family activities (example, family going to a movie or out to dinner together).
Money for clothes, entertainment, incidental spending, specialized "equipment" like football cleats is generally expected to be provided by the student's parents.