We replaced our old screens with new a few months ago at Thunderbolt Marine
Boatyard in Savannah, Georgia
The guy who did it charged approx. $250 total and took about an hour to do all of them while on the hard
As said in other posts, this material should be relatively easy to source, perhaps, even online. It's not expensive.
The guy who installed didn't seam to have much trouble pulling the stickers off. Once that was done, and he'd cleaned the window, he sprayed the substance that is available for boat registration
installs to give him a bit of ease in moving the new sticker into place while removing any wrinkles.
He then used a new razor knife to cut the perimeter of the sticker so that it fit perfectly to the shape of the window.
The material comes in rolls, so he would cut for each window's width (left to right measurement), apply it, then cut as described above.
Alternatively, as others have mentioned. Once you have the sticker off, you could apply a sticker to the interior
side of the window, thus taking the typical sources of wear and tear out of the mix. Although the sticker would need its adhesive
side facing the window, obviously,
The last option I've seen use, is to remove the old sticker and replace on the interior
car window tint stickers, which, supposedly will keep sunlight from heating
up the boat
, be dark enough for most people's privacy needs, and creates an different look (dark windows) for your boat.