This is an interesting question. You may need to go to the tint shop and get the band premeasured and cut out. Then you would bring that band over to the graphics shop and have them cut out the lettering or graphics you desire. Then you could either put that strip on by yourself or take it back to the tint shop and have them put it on. Or you could just buy the tint at an automotive store, cut it yourself, and bring it to the graphics shop... and then put it on by yourself later on. So many options!
The only thing I would be concerned about is legality. I do not know where you are located (sorry if you mentioned it before), but in California it's actually illegal to have that strip of tint on the top of your windshield - no matter how wide. If the actual windshield glass is tinted by the factory (usually translucent green or blue), that is ok. But at least in California, I know it's illegal to have that front strip added on afterwards. I've never known anybody to get a ticket for it but ... to be forewarned is better than not knowing at all. I guess.