Linden Lab recently announced that they are formalizing a price decrease of 50% for educational or non-profit organizations. This includes the private region setup and maintenance costs. The discount applies to full regions, open spaces, and homesteads. This change really just makes the benefit more easily accessible by more of these groups. With a minimum of 6 months you can also qualify for invoicing.
To be eligible you must send proof of educational accreditation or non-profit status along with a government-issued photo ID to email@example.com or firstname.lastname@example.org.