Resources used by inactive Game Objects, many weapons

I am making FPS. With many weapons. Like 100+ . I wonder what is the best way of implementing them into a game. I have two main ideas. First is just adding Game Objects to scene and disactivating them when not used and second is adding one object and changing its model everytime I switch weapon, but I guess that would be confusing at least for me. And I don't really know how I would do that.

My question is: what is the best way to add many weapons in Unity? Does inactive gameobjects take much resources?