These art supply stores in your area should sell drawing materials such as pencils, paper, and erasers (like the 'kneaded' eraser, everybody's favorite in class!):
Watsonville:
Wild Rose
1929 Main Street
Watsonville, CA 95076
Art Supply (831) 722-4282
Salinas:
Michael's
121 General Stillwell Dr
Marina, CA 93933-6242
(831) 384-0562
860 Northridge Shopping Center
Salinas, CA 93906-2007
(831) 442-3506