Ask HN: What are the differences between a $485 and a $40.000 eye tracker?

I am fairly new to eye-tracking and wonder if I should get my own equipment after some studies at the university. The main questions for me is: What are the main differences between a $485 (e.g. http://gazept.com/products/)and a $40.000 solution (e.g. tobii X2 - tobii.com)?