I think these are the finest of the premium California oils. Prices may vary with individual stores.

McEvoy of Marin Olive Oil
Fresh and harmonious with herbal flavors and a slight, pleasant bitterness in the finish. ($40 for 750 ml.; $15 for 250 ml.)
DaVero Extra Virgin
Well-balanced, with fresh green fruit flavors and a pleasant pungency. ($18 to $20 for 375 ml.)
Lila Jaeger's Olive Oil
From an old orchard of 100-year-old trees, soft, sweet, rather buttery, with clean fruit flavors and a pleasantly bitter edge. ($18 to $20 for 375 ml.)
Frantoio
Soft, sweet, with lushly fruity flavors. ($14 to $15 for 500 ml.)
Stutz 1997 Mission Reserve
Unfiltered single-varietal with light fruit flavors and a hint of almonds--contradicting the belief that Mission olives can't produce a fine oil. ($18 for 375 ml.)
B.R. Cohn Sonoma Estate
Smooth, soft, lightly fruity, but a trifle bland, in a hand-etched bottle. ($50 for 500 ml.)

Mail-order sources:
Oakville Grocery, 800-455-2305
Strictly Olive Oil, 800-930-0077