You can get a handicap through most local public golf clubs without being a member. Or through GHIN/Gap:
Sign up through GHIN.com or gapgolf.org (Use GAP as the organization)
You need 5 rounds within the past year to get a handicap index, but 10 rounds are recommended.
COST: $45.00 for a 12-month membership to the USGA/GAP GC
ADDRESS: 1974 Sproul Road Suite 400
Broomall, PA 19008
CONTACT: GAP Member Services
PHONE: (610) 687-2340
EMAIL: membership@gapgolf.org
WEBSITE: www.gapgolf.org