Cost of mining has no impact on the actual cost of gold. Clearly you should get that in your head; if you ever did you would see why you keep on being on the losing end. Reserves of gold in the world are huge. Just look at the oil sands or natural gas and you will see why commodity costs doesn't matter. If it's not profitable to mine, it simply won't be mined, which at the same time, doesn't get the company profits. Again, that's another reason why gold mining companies are such a poor investment.
Again, there is not a single gold mining company with enough of a monopoly that will be able to affect the cost of gold. Barrick Gold is not OPEC. Even OPEC is marginalized nowadays.