Having used a dealer/agent since I began collecting ancient coins in 2007, I can state factually that my actual experience with my dealer is the opposite of the assertions made in this post. So for those who may be considering the use of an agent, my own experience may be helpful in determining whether you might want to use one yourself. First, my use of a dealer is based on two premises that may or may not apply to others: (1) The coins in which I'm interested are all in the $1000+ range -- usually in a higher range -- and my experience may not be applicable to coins under that range. (2) Even after 14 years of viewing, researching, and collecting ancient coins, I still do not consider myself to have sufficient expertise to fully evaluate potential coin acquisitions in the price range of coins that I collect. For those collectors who are actual experts in the types of coins they collect, it's understandable that they would forego the use of an agent. Since my dealer is very well known in the ancient coin community, neither his presence at any particular auction, nor his bidding on any particular coin, has had any positive or negative effect on inducing other collectors or agents to bid on coins in which they otherwise have no interest. Every other collector with whom I've discussed this issue has, like me, discussed his/her maximum budget for each auction coin with their respective dealer prior to the auction. Attendees at the auction know this, and the likelihood that a known dealer bidding on a certain coin will increase the interest in that coin is, well, vanishingly close to zero. In addition, the dealer may be trying to acquire the coin for his/her own inventory, in which case he/she will be very unlikely to overbid on that coin. So if you use a reputable agent, you can be comfortable that your agent isn't affecting a coin's ultimate hammer price. By using an agent who attends the auction and views the coins in hand, it becomes irrelevant whether you trust the auctioneer's pictures and written description. Your agent's personal evaluation of the coin will be the most important information in helping you decide whether or not to bid on the coin, and how much to bid. This is one of the most valuable aspects of having an agent, especially if the agent knows your collection and your preferences. More than once my dealer has incremented my top bid slightly, during the auction, when he thought he could win the coin and was confident I would want it for my collection. His instinct was spot on in these situations. Frequently he's viewed a coin in hand and recommended against it, or a lower maximum bid, based on his evaluation and knowledge of the ancient coin market -- i.e., there may be other coins coming up in the future that are equal or better for my collection. This is expertise that I don't have, and for which I willingly pay a fee. Finally, for all the reasons pointed out by others in this thread, bidding live in person at an auction is much more efficient than remotely via phone or the Internet. If you can't attend yourself along with your agent, having a live representative at the auction is a huge plus especially for those coins that are important for your collection.