I would definitely have bought one of these Tobii Eye trackers too if it had OSX support. My guess would that the hold up on OSX is related to Apple Patents more than anything else. See: http://www.patentlyapple.com/patently-apple/2013/10/apple-files-eye-tracking-system-with-advanced-gaze-controls.html
For now I’m also going to have to try the Eye Tribe and see how things go.