No, it's not a secret website or bookstore... think more local than that. Yes, your local library! Have you checked out your local library's collection of knitting books yet? If not, I highly encourage you to get online and see what's available in the catalog.
These are the books I currently have checked out. Now, I live in a decent sized city, so I can request books from quite a few libraries in my system, but I never would have imagined the selection to be so good. In the past I have checked out stitch dictionaries, books about Estonian lace, color-working and finishing techniques. And the best part of it all... it's free!!