Some wholesale stores set minimum quantities or spend values for their B2B customers. You can do this by using WooCommerce Wholesale Pro with our other plugin, WooCommerce Quantity Manager.
This lets you set min/max quantity rules and spend values, either globally or for specific products, categories or variations. You can also use it to set quantity increments and step values - for example, for products that can only be bought in certain groupings.
You can set up these quantity rules for all your customers, or enable them for the wholesale roles only.