http://www.themirt.com/ It costs 300$ but you can build your own for under 20$ here: http://www.i-hacked.com/content/view/176/44/
Not to mention that almost all intersections that are set up with a MIRT receiver ALSO have a CAMERA that is triggered by the MIRT. Use one illegally, and you WILL get caught. The device described in the DIY article will NOT work anymore. Modern MIRT signals require a modulated digital code (similar to a TV remote control), not just a pulsed IR source.
