As of Sales Pack v2.0.
Suppliers can be accessed at Products > the top right menu > Suppliers or Purchase Orders > the top right menu > Suppliers. It's also possible add a navbar tab.
Access to Suppliers is controlled by Roles.
It's possible to specify Supplier Prices for specific products. There can be multiple prices for the same product: for specific date range or quantity.
Whenever a product is added to a Purchase Order, the system will look up the price in the associated Supplier.