When buying gold or silver online at sites such as EBay from a dealer, expect to pay a premium over spot. That premium is a convenience fee to obtain your gold or silver bullion. You are expected to retain your gold or silver bullion for a length of time to where the current spot price is equal to, or greater than what you paid for it.
When buying from an individual on EBay, the individual should expect to get no more than spot price, and even maybe a little less than spot. The individual has no claim to anything more than spot price.
Too many people fall into the EBay trap of paying a premium to an individual. Do your research folks! In many cases you can buy the gold or silver bullion you want cheaper from a dealer either on EBay or from their web site.
When bidding on any auction, whether from a dealer or an individual, pay close attention to current spot prices. You should not be bidding any more than that or maybe a little higher. But be careful, bid too high and you could be paying more than you would buying direct from a dealer. In other words, do your research!