Food Bookstore in SF, Marin, or East Bay?
Mo's on Telegraph had a huge section last time I was there trading in cookbooks for store credit.
They're mainly used books, but many are in perfect shape. They've always had a very wide and eclectic selection of cookbooks.
The most interesting thing was that I tried to trade in the French Laundry Cookbook and they wouldn't take it. They said they already had more copies than they knew what to do with. They said they'd take it in their charity donation box.