U.S. Auctions
In the U.S., a number of auctioneers such as Bonhams offer numismatic auctions on a regular basis. A general numismatic auction will usually be broken into sections such as U.S. coins, paper money and world coins. Ancient coins may be be included in the world coin section, or be given a separate section of their own. See the Coin World website (see Resources) for a list of upcoming numismatic auctions.
European Auctions
Among British auctioneers, Dix Noonan Webb holds at least one specialist ancient coin sale every year as well as general numismatic sales, while Spink auction coins and stamps internationally. For a list of other European coin sales, visit the Aucteam website (see Resources).
Online Auctions
Many commercial numismatic websites--i.e., online coin stores--offer an additional service to their customers in the shape of weekly online auctions, including ancient coins among the lots.
Bidding at Auction
If you can't be there on the day of the sale, you can leave a maximum bid with the auctioneer. Alternatively, you can arrange beforehand to bid online or by telephone. If you are successful, it will then be your responsibility to provide transport for your goods. You will also have to pay a buyer's premium, which can be as much as 20 percent of the hammer price.