ireefny has a used 1/2 hp Pacific Coast chiller FS and he lives in the same town as you!
Also, if you keep MH lighting, 1/4 hp will not be enough for your tank size. I use a 1/4 hp on my 120g with 250w MH & VHO lighting and the 1/4 hp takes about 1.5 hrs to drop 3 degrees.