If I can't find it locally I get a lot of my tig supplies on-line at;
https://www.arc-zone.com/
Are you looking for just screen or the complete gas lens collet body (with the screen)?
Collet bodys are not too expensive - $5 to $10 depending on size & brand. I don't remember seeing just the screen. It might be a trick to get it attached to your collet body? Maybe not - I've never thought about replacing just the screen.
I've always had good service from Arc-Zone. And they usually have OEM and/or quality parts.
They have nice assortments of different things too (like an assortment of sizes/types of tungsten or an assortment of collet bodies and cups, etc.).
They always include a bag of M&Ms with your order too!