Hello, would there be a trick to set a minimum item quantity during a transaction? For example not being able to buy less than 1000 stones without creating this limit for other items? And both in purchase and sale?
Thank you

You could set up each item with the desired amount in the command blocks and then set a cooldown for each one to limit when the next time they could buy it as well. Cooldowns are done in seconds so 600 seconds is like 10min.

Instead of being "Command": null,

you do [" inventory.giveto $player.id short name amount "]

Example below

"Wolf Headdress": {
"DisplayName": "Wolf Headdress",
"Shortname": "hat.wolf",
"EnableBuy": true,
"EnableSell": true,
"Image": "https://rustlabs.com/img/items180/hat.wolf.png",
"SellPrice": 1.0,
"BuyPrice": 1.0,
"BuyCooldown": 0,
"SellCooldown": 0,
"KitName": null,
"Command": ["inventory.giveto $player.id hat.wolf 2"],
"SkinId": 0
},

The only issue in doing this is that I have made it so that you cannot sell commands (to stop other issues).

So I need to finish the limiter feature. Sorry for the inconvenience 

The latest update allows you to set each item buy/sell amount button generation now. (instead of global maybe this will help you a bit?)