Hi Rebekah,
The main factors that effect prospective volunteers when looking for work
in South America are the length of time they can volunteer for and their
language (Spanish or Portuguese) skills. You have all of that covered so
I don't think you will have a problem finding worthwhile volunteer work
in South America.
It sounds like you want work in different fields so here are some suggestions:
(I have heard good reports about all these volunteer organisations).
Working with children/street-kids (Cusco Peru):
Aldea Yanapay The House of the people of the sun
Working with children long-term commitment reqd. in Bolivia:
Amanecer Cochabamba Bolivia
Working with Animals:
Comunidad Inti Wara Yassi - Portada - Organización para el reconocimiento ecológico Boliviano y el voluntariado por la vida animal salvaje(Bolivia)
Santa Martha - Animal Conservation Supported by Volunteers in South America (Ecuador)
Karumbé (Uruguay, Sea Turtles)
Working with Indigenious Communities:
Volunteer Torewa - Madidi National Park (Bolivia)
I don't think you will have any major expenses. In all the above programs
you either support yourself while volunteering (i.e. pay for a hostal + food)
or you live-in and pay fairly low-level fees,
e.g. intiwarayassi.org charge ~USD$200 per month.
If you can commit to 3-6 months volunteering, some organisations (mainly kids-based programs)
can offer free accommodation to volunteers (with good Spanish).
There are a more of these type programs in Central america if you are interested.
HTH
Steve
www.volunteersouthamerica.net