You probably won't. The majority of a gold coin's value is numismatic value - not intrinsic or precious metal value. Of course this is not true with modern bullion coins or common date older & lower grade gold coins. Often these coins only increase in value as the price of gold increases. For example - a tougher date $2.50 gold Indian with .1209 oz of gold may sell for several hundred dollars but only contain, even at today's prices, $70 worth of gold. So even if gold increased by another $50 an oz the value of the coin wouldn't change.
I have always been a believer in collecting gold coins that sell at modest premiums to the bullion value for this very reason. It is often better to own two lower mint state coins than one higher mint state coin for the same money. I know that common wisdom is to buy the best you can afford, but when I check prices between 1980 and 2005 this doesn't seem to be the case. There are exceptions for certain dates, but in general the price performance is similar on a percentage basis, so owning a larger number of ounces for the same cash outlay is safer than relying on continuing and expanding numismatic premiums. Of course, this won't be satisfactory for collectors who want only the best, but it works for me.
