If people can sell ammo for twice what it is worth they will.
Remember economics. An item is worth whatever people will pay for it. If people are consistently paying "twice what something is worth" then it's original "worth" was miscalculated, and the market has corrected the mistake. That's the basis of capitalism .
Is it even possible to sell something for "twice the market price". Presumably,they mean the free market price,as the very statement implies that people are allowed to sell for whatever they think they can get. (Notice,its not "whatever they think is fair,as your certainly allowed to buy something and sell it for a price you think is downright unfair,just as a used car salesman. He KNOWS what he paid for that 97 Chevy and its no where near what you paid for it) The very definition of the market price is whatever price people are willing to pay and the seller is willing to sell for. If his products don't sell,its assumed that he will sell for less,if they all sell out,hes going to edge that price up and see if he can still sell them all. Thats why I don't get angry at the gas station when I see gas at 4 dollars a gallon. Most make a few cents a gallon on it and hope to sell Slurpies and sodas to turn a profit. (its the same with lottery tickets,they are to bring you in and hopefully sell you some outrageously overpriced grocery items or a soft drink or a case of beer) I get angry at the guy next to me whose also grumbling about the prices,by himself,driving a giant SUV that gets 11MPG.
In the case of ammo,I cant really be angry at anyone. Its just the way it is. People are afraid there is going to be a giant tax or some sort of ban and they want to get what they need now and the factories cant keep up with demand in some cases. (Walmart here has ammo in stock most of the time now) I think they are going overboard or making bad decisions in many cases,but I cant really fault them for trying to look out for themselves. Personally,I think your a fool to stockpile thousands of rounds of retail ammunition. Perhaps surplus ammo like the spam cans of 7.62x54R make a little more sense,but stockpiling 20 dollar a box retail ammo is just being short sighted. For the cost of 10 boxes,you can buy all the stuff you need to reload your own ammo,including the equipment to cast bullets. Then you can stockpile enough brass powder and primers to last you forever. If you need gas checks,you can either stockpile them,or if you really had to,you could make them with a punch and a sheet of copper. (If your really desperate,you CAN get by without them) Actually,if you were REALLY desperate,you could go back to paper patched cast lead 45-70 loaded with home made black powder and the only thing that would give you grief would be primers,which again,if you were desperate enough,you could make with a punch,a sheet of brass and some knowledge of chemistry (and some risk of blowing your hand off). You would just need to get yourself some berdan brass as berdan primers would be a lot easier to make.
Wow,that gives me a crazy,and probably dangerous idea. You could in theory,if you were crazy enough,make new berdan primers from sheet brass, and the priming compound from boxer primers,but I'm not going to go there because it IS a crazy and dangerous idea which is why I will leave it at a intellectual exercise and not actually try it.