Hi @my5tery, thanks for your understanding. As the EyeX is now deprecated technology I am afraid that support on this platform for Linux is highly unlikely especially as the EyeX requires a powered USB3 Port and a more complicated driver software making implementation difficult.
Regarding pricing, the Tobii 4C currently retails at 169 EUR however it may worth your time reaching out the sales department @ https://help.tobii.com/hc/en-us/requests/new to see if there is a possibility of a special discounted price as an upgrade from your EyeX. Best Wishes.