The more I post on here and the more people get to know me... they will find out one important thing about me : I'm pretty dang frugal.
So paying $100 for something like this is out of the question.
I'm talking more along the lines of DIY.
Also, every time you type in all caps a kitten is run over by a bulldozer.
I too use a keypad mounted on the garage door frame....pretty easy. I do remember seeing an article one time about buying an extra door opener and taking it apart. IF you are handy with soldering small wires, you solder two wires to the door opener and hook up a momentary pushbutton in parallel with the button on the garage door opener remote.
I have an even simpler way to open my garage door.
A magnetic reed switch hidden within the wooden door frame.Place a small magnet over the exact location of the reed switch and the door opens.
An intruder will never even think of this let alone be able to find the magnet or the location of the switch.
I made one years ago just like the link you have in your post. Since I don't use my high beam much at all (only for opening the garage really) I just wire the remote directly to the high beam now. Using the high beam trigger is an excellent idea for opening the garage door. I've been using this for years for both my cars and bikes. If anyone is interested I put some pics on my site along with some notes. Basically you solder the connection on a garage door opener remote to closed so that it is always on, then you solder wires to where the battery goes and connect it to your headlight high beam wire. Whenever you flash the headlight it energizes the remote and the garage door opens (or closes). Hope this helps someone.
Here is the link to my site. http://willsell.com/gdo/