A buyer's premium is a fee, usually a percentage of the bid price, which is paid with and added onto the successful bid amount. Either broker, listing or selling, can be the responsible broker. However, one must be identified in a licensed transaction. Yes, in theory. However, it must be pursuant to agreement between the brokers in writing, and the responsibilities of each brokerage and the licensee should be carefully spelled out, including identification of responsible broker.
Auctioneers structure real estate auctions differently.
Be aware of the fact that bidders coming to an auction without a real estate licensee, or those who preregister through a licensee, may already have some kind of buyer broker contract and some type of commission or fee obligation to a licensee. If any person is engaged, whether or not through an auction mechanism, in licensed real estate activity in the state of Idaho, a real estate broker's license is required.