I got additional tint while I am down in AZ...like Josh said, "worth every penny." It is under warranty and cheap for my rear and CR Laurance awning windows...VA has ridiculous tint laws so it would have cost me double to get a barely noticeable tint on driver and passenger side as well as the windshield. Wasn't worth it to me at the time, but I love my read windows and my CR Laurance windows tinted.
I've done tinted windows for all our cars, trucks and now PM over yrs and cost 1/3 of those shops charged. it's very easy to do but i do recommend very sharp blade. There are lots of videos out there how to do it and it does take time and experience to do it right. i did my PM both side in less hr and very easy since these windows are flats. Texas requires that you must have at least 25% of light go through the tinted windows on the driver/passenger side but on the rear windows you can tinted as dark as you like
Check your law. NH is no tint on the driver’s and passenger’s windows. That and the fine is $300 so the nice officer told me in my AZ sourced car. It’s unnecessary there anyway. Here in AZ it seems to be tint ‘till ya don’t squint!
It is doable, but not quite as easy as it looks. I've done it (in the business on the manufacturing side), and it helps to practice or know what you are doing. In general, I don't think it is that easy to source the better quality window films. Not saying that it can't be done, but you would need connections to get them. If you are only talking about the front driver and passenger side, I would get it done by a pro in one of the higher VLT films that block most all of the IR. These films are warranted for life, so it is something that will last you a long time. Make sure you comply with the laws of the state you are in, which should not be an issue with the films I noted.