So you have a gouger or two. Don't delude yourself that the way to deal with evil is simply to forbid it. That is the core of what we now call "liberalism", though it is extremely illiberal in the classical sense. What happens in the free market is that somebody else who has batteries will sell at a slightly lower price than the gouger, in an attempt to scoop the business, just as happens in normal times. Of course, the resultant price is higher than normal, but that reflects the difficulties inherent in providing emergency supplies on-demand in an emergency situation.
Now, once you pass a law forbidding "gouging", what is that supposed to accomplish? How is it supposed to be adjudicated? I suppose that the all-powerful tribunals will assemble whenever needed, at a moment's notice, in front of the coppertop display rack, not though the powerlines are all down, the streets impassable, and naked children are gathering at the rear of the store trying to get the generator started.
No, of course not. What will happen is that after everything is back to "normal", the lawyers come out of hiding and start litigating for damages against the hapless dweebs who marked up their batteries 50% (because they didn't know how long it would take to get any more, and if you can't get 'em, you can't sell 'em, and you can kiss the income good-bye as well!) The legal feeding frenzy can effectively discourage anybody from wanting to make the effort to sell anything, given that doing so makes you an automatic target.
Here's something to chew on: Ask yourself, why is it that once somebody has proposed a law or some other government action in response to a situation, that effectively seems to end the discussion? What is this universal assumption that once a government solution is proposed, everything else is off the table? Why is it that all problems flow downward toward more government, like water seeking its own level?
Free men in a free country, in reliance upon God their Maker, always find a just and equitable solution that fits the need. Government, OTOH, provides "solutions" that exploit the need, and for whose benefit? (Nobody asks, do they?)
As long as you treat the "government" option as the end of the line, after which you may consider the problem as well and truly in hand (after all, somebody is getting paid to fix it now!), the true character of government solutions will remain hidden to you, and the power of freedom will seem mythical.
What are your thoughts about the need for and imposistion of martial law?