There will eventually come a time when you have to sell your gold coins. Be it for financial reasons or just the fact that you have completed a set and want to get financing to start up a new collection. When it is time to sell gold coins, you obviously want to make sure that you are getting the best price. That being the case, there may not be a better place to use as a marketplace than the Internet.
In all likelihood, when you wanted to buy gold coins, the Internet provided the outlet. While people still obviously buy from brick and mortar dealers, the selections are limited and the price is the price. Comparison-shopping on the Internet will provide a much better selection and of course, discount pricing.
The same can be said when it is time to sell gold coins. The first outlet would be to shop the coins from dealer to dealer. This would work in much the same way as if you were to go from store to store. Take scans and or detailed pictures of every coin that is to be sold and send them off to the various dealers for an estimate as to what they would offer. It is like going store to store, only you never need to leave your house.
The second outlet is going to be auction or collection sites. This will enable you to either post the coin for the value that is desired or to put it up at a low number and let the collectors go to war and bid the coins up. This can be a risky move, but it will sometimes show a bounty much higher than any storeowner would be willing to pay. It is just a matter of catching the right collector at the moment when they truly need the coin and have no problems paying a few extra dollars for it.
The truth of the matter is that the days of walking into the local pawnshop or coin dealer store to sell gold coins is long gone. There is little to no value in selling your coins in that manner. The dealer will go as low as possible and hope for desperation to close the deal. Do some research and see what the coins are going for on other sites and then choose your outlet. You are all but guaranteed to get a much higher price by selling gold coins in this manner.