I suspect interest in blue tint would be somewhat limited, as it would appear that the vast majority of S30s sold in Australia have clear glass.
It's Zeds that have come in from other markets like NZ, Japan and wherever that have the blue tint, and I don't suppose there are very many of those.
No doubt there will be some cars being restored to a thoroughbred standard and requiring fresh new unblemished glass, but should an owner decide to go for the blue tint option then of course a full set would be needed including windscreen but as you've pointed out large numbers of those would be required to be economic.
Never mind, as least we have you as both a Zed owner and a glass supplier on the forum.
You said above that you have side and rear glass coming, keep us posted.