The buying desk is an added paid feature.

a) If you don't opt for this feature, whenever a buyer cannot find an item/service on the platform, they will be directed to submit a request to the IBM B2B Commerce for Procurement team to have the item/seller added to the catalog.
b) If you opt for this feature, whenever a buyer cannot find an item/service on the platform, they can submit a request to source services, which will be sent directly to the buying desk to conduct 3-bids-and-a-buy