Well, there's the big thing. How long is long enough to convince someone? Obviously, if it starts bubbling in weeks, it's ass. But say you get 5-6 years out of DIY. I'd say you've done good. $35 shipped for my GP tint, and I don't think I'll have the car for more than 5-6 years anyway. So if the tint outlasts the car, I'll be ordering a DIY set for the replacement vehicle.