When I go to buy a DLC item, I see this. Please see screenshot.
Do you own the DLC?
You cannot but a DLC ingame.
You have to use the Steam shop.
This Screen is just for unlocking schematics to become able to craft those DLC items.
It is shown even if you don’t own the DLC.
On one hand I don’t like that you see that even if you don’t own a DLC because of this misunderstanding, on the other hand it is good to see which items are available by buying a DLC.
But, I don’t have all the DLCs.
And thanks to your post, I can see that very likely I don’t have the DLC that brings in the weapons that I wanted to buy.