Well, i got the part that ammunations are taken as businesses, but can there be a part when you go on streets
"/gunad Selling minigun 40 10000",
then a message come to the main chat -
"Andre9977 is selling a minigun with 40 bullets for 10000 Argonath Dollars"
When you got a deal, you meet up with buyer, you do "/givegun id minigun 40" and the player is now going to pay you (Paying not scripted) 10k.