Adorama has the B+W 77mm Circular Polarizer MRC Filter for $64.95. It regularly sells for $74.95-$79.95. Free shipping.
77mm is a very popular filter size (and this filter can be shared by many Canon lenses). This filter has a Multi-Resistant Coating (MRC).
This is an okay price. December at $50 from B&H was pretty nice. And it was Kaesemann.
Yes, I had to look up my model, because I bought 2 of those from B&H then! 😉