For more affordable and open-source alternatives, you might be interested in Pupil Labs[0].
How much are the Tobii glasses if Pupil Labs' are almost 6 thousand Euro?!
It uses a convolutional neural network to detect the pupil location, which is a lot cheaper in addition to running real time (for controlling IoT devices around the house). The website shows the 3d printed prototype, injection molded mass production coming in about two months, probl also on kickstarter. We'll open source our libraries in Python, JavaScript, C++, Arduino, Dart (Flutter) to connect to it with MQTT to all DIY projects that can benefit from eye control. In addition to gaze location, the scene camera can detect ARUCO markers and QR-codes. The battery lasts about 10hrs.
Email me at jschreuder@kexxu.com if you want early access.
Pupil Labs have their code on github (you can also use it with none pupillabs cameras :). It's python and easy to change /extend. here's the repo: https://github.com/Pupil-Labs/Pupil
Check also the branches and who forked it ... there are a lot of experimental eyetracking and other algs implemented.
We already used them for a lot of research projects (implementing smooth pursuit interactions and similar).
Edit: added the github repo of the desktop software.