Xshen, the foothill one is closest to you in Arcadia. They had lots of apricots last weekend, and other stone fruits. That one meets only every 2 months though.
I'd imagine the LA and OC ones are far for you unless you work there or happen to go that way on the weekend.
I tried grafting apricot for the first time last weekend and the wood on the small twig of a scion was tougher than I imagined. Normally I do cherimoya, white sapote and soft things like that.