Supplier items can be searched for under the Supplier account or the Item search .
Open the supplier's Account.
Click on Purchasing in the side navigation and select Range for a list of items from this supplier. Note: At least one supplier item must first be created for this account from a master item so that the Purchasing tab will appear in the side navigation. (Create a new supplier item in the master item)
Click on Items > Search > Supplier items for a list of all supplier items.
Narrow your search by specifying a Supplier, or an Item.