I've seen it done - pros are amazing with it.
It's somewhat similar to applying contact paper. Prices I've seen are typically $165 to $200 for all 4 windows. You would pay probably at least $75 for all 4 windows for the film alone.
The pro's and the guys on YouTube make it look like it's just slap it on and squeegee it out and you're done, but it's not that easy. The guys on Sunday kick 50-yard field goals with no problem either - but that doesn't mean I could do it.