I am not sure you understand the basics of gold mining! While costs have truly risen no where near what you are seeing. As stated gold mining companies tend to be general business idiots. If you have a mine with average grade of 2 gpt and the price rises you do not mine the 2 gpt but instead the 1 gpt waste which is now profitable though barely hence they always underperform the price of the commodity!
Similarly when the price of gold falls gold stocks can out perform the commodity depending on who they are and what grades they actually can mine which is what you should consider before investing. It limits risk. For example right now you can buy a company like VTR dirt cheap basically 52 week low with 5 million low grade ounces. However, they could actually mine 2 million of that with about a 50% higher grade! So the risk from here at their 52 week low is less than say someone that really has no economic choice what to mine!
Its all about risk reward check the cut-off grades! For example if a company has 4 million ounces at a 1 gpt cut off and only has 1 million at a 1.2 gpt cutoff the smarter investment would be a similar company with 3 million ounces at 1.2 gpt!
As I stated check their technical reports at a given cut off to know your risks!