I think it is a matter of level. I think in normal times, the gun shops I like best provide great service and offer slight discounts from retail list. During a shortage, some still offer a slight discount, but I can certainly understand them asking full retail price and wouldn't consider that gouging. If they are to the point where they cannot get enough merchandise to maintain their business or are dealing in collectables, they may even charge a slight premium.
I think where it become unethical is when they try to truly take advantage of a scare and try to charge more than 20% over list. I don't support these shops with my business.