eBay
Facebooks Glastron groups
Great lakes Skipper ..
https://greatlakesskipper.com/Craigslist, maybe find one with a bad motor that sat out side uncovered for (kind of) cheap.
You might be able to use Searchtempest for your search on CL & eBay.
They might have used that same windshield on other years and models.
I don't have any info on the newer Glastron models.