I bring my own wine (and have been doing so for 10 years) at least half the time. In my area of Nor Cal $10 corkage is fair $15 is normal and $20 is pushing it. There are a few restaurants that pride themselves on having $0 corkage. Those same places also have fantastic values on their wine list (wines priced at retail so they are still making money) so I often don't bring a bottle just to enjoy their great wine list.