After 6 months you don't have to apply for a work permit. You can continue to renew your visitor visa except the price is 100BZ.

The amount of money it will take to live in San Pedro or anyplace in Belize will vary greatly depending on what you consider necessary expenditures. Many people like to have a few beers in the evening greatly increasing your expenses. Many love scuba diving which is also expensive.

If you come on the QRP visa I don't believe you can work even as a volunteer. Much of this is covered in previous thread do an extensive search.