I do not personally know of any training centers in California, but I live near Chicago.  Have you checked ASNT's website and looked under learning for educational institutes?  They have a list from colleges to industrial/commercial training centers.  I have seen several training centers listed in California, Oregon and Washington.  For a good introduction to basic/Level I UT, check out:
http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Introduction/description.htm

I ATTENDED THE LEVEL I AND II SALT LAKE CITY, EXCELLENT COURSE.

http://www.geinspectiontechnologies.com/en/training/course_list.html