your logic is off in multiple ways. First of all those are clearly smaller than normal camels. second a camel is of a different density than gold, you would want to do it by volume. Those look to be about 1x.5x.5 m = 250,000 cm^3, gold has a density of 19.3 g per cm^3 for a total mass per camel of 4.825 million grams and a per camel value of 6,471,676,000 * 75 = 485,375,700,000 US dollars. Of course that is for the modern price of gold, the total gold supply was much lower at the time but also so was demand so who knows.