I agree that it might seem like a lot for people who haven't often paid corkage fees, but the restaurants don't want you to bring in your own wine. They want you to order off of their list so they can make a profit. The "sweet spot" price should be one that is high enough to prevent people from bringing in their own "non-special" wine, but not so high that it makes people not want to dine there.

Case in point, I worked for a long time at a nicer restaurant that didn't have any corkage. Regular guests would go to the liquor store and buy the exact same bottle of wine as was on our list, come in and drink it, and then not tip at all on the bottle of wine. A corkage fee with some substance would have prevented that.

Chris