Font smoothing in system prefs
I had the opposite problem... fonts in iTunes weren't using anti-aliasing, and looked chunky and horrible. I fixed it by adjusting my system preferences settings for font smoothing (it is under the General tab). Mine was set to 12 (which turns off smoothing/anti-aliasing for any fonts smaller than 12 point). I changed this to 8, and now iTunes looks much better (non retina).