For excellent information on the cost of living and other important things people need to know about living in Costa Rica, please go to this site (Retire For Less in Costa Rica).
Paul and Gloria Yeatman live in San Ramon, in the Central Valley. They offer sensible advice on how to live here on a budget and still enjoy everything this wonderful country has to give us. They have kept meticulous records on their spending since arriving here in 2009 from Boston. They have embraced Costa Rica - the people and the culture.
We have the same mindset as Paul and Gloria. They are super people and great friends.