Kaesemann isn't the only option for multicoated CPLs. B+W makes non-Kaesemann MRC circular polarizers. The B+W MRC 58 mm CPL is $93.50 at B&H; the 67 mm is $117. If you're looking for a CPL for your 10-20, however, bear in mind that it'll give you a very uneven effect across a clear sky since that lens covers such a wide AoV that you'll be able to see the difference between a CPL at right angles to the sun and one aimed along the line of the sun. For that you'd be better off with a graduated ND filter (square, not round) to hold back the sky.