The first thing I am suggesting is https://www.gmodstore.com/scripts/view/1804/
It is a cool way to give something to do while waiting for people to come to your store and it is just an all around cool idea with some applications in base defense and raiding.
The second thing that is more shit and probably will be hated by most is https://www.gmodstore.com/scripts/view/3864/
I don't think it will stop self supply or anything, I think it will give more of a demand for guns and make them more valuable because they now take time to make. It also will give more haggling potential and there will be no definite price.
(if you don't like that this is 1 suggestion blame quartz)