Squarespace Commerce isn't optimized for wholesale shopping with member logins or separate wholesale pricing for products. Squarespace engineers are always looking for ways to improve the platform and are aware that this is a feature that users are interested in.
You can write into customer care to put in a feature request by following the link here:
In the meantime, as a workaround you can use a password to protect a page that houses wholesale priced products. To do this, you would first need to create a second version of each product and mark that with the wholesale price. You are able to duplicate products and then edit the price and information.
There's a handy guide on duplicating products here:
You could then move the wholesale products to a new page. To do this, go to the Product Page that houses the wholesale products > select the product/s you'd like to move > click Move Items near the bottom of the panel > choose the new product page that you'd like to move them to.
There's a handy guide available here to help you through the process:
Each product, retail and wholesale, would have it's own separate inventory when using this method so you would need to manage the product inventory manually outside of Squarespace.
Once you've created the page with the wholesale prices, you can protect it behind a password. We have a helpful guide for this here:
You can then supply that password to your wholesale clients in order for them to shop and purchase the wholesale priced products.