You maybe didn't want to use money on weapons, theres no other way on getting the weapon other than trading an item or another weapon.
For example, You might have wanted a Sniper Rifles, so you would've had to trade in atleast 5spases and 2m4's, if the dealer agrees with it, the spases and the m4 would be automatically replaced from your locker and you would be given the sniper rifle in hand. You might not want to trade in a weapon for a weapon, you might want to trade in some valuable items such as 250pot for a shotgun. You might be thinking that's too much and its true, but remember, 60 pot is $1200 due to 1 seed. Around 240pot it would be $4800. Thats probably the ammount of a Shotgun. This suggestion is not something for an advantage to players as they are giving more in return for the weapon they want. They can also trade in materials for weapons, BUT! normally its 500b given to a arms dealer from a mathandler for a Shotgun. This place, you must give atleast 700b for a Shotgun or more.
So what ya think?
When you go the Sewers and find the entrance>>
You must go to the arrow near the dealer and a Box will pop up like this>>
It will give you the options that they have in stock! This is like Car Dealerships, they might not have the car you want. Here, its the weapon you want that might not be in stock. The more the trade, the more the stocking increases. It should be update atleast every 1 hour.
This is the interior that should be placed for this market.