But I digress.
One thing short story authors really struggle with is money spent on cover art. When cracking out a new story every week or month, it's simply not practical to spend $300 on every cover unless you're making gobs of money from some other job that you have.
BUT... good quality cover art can make you money. People are shallow. I'm shallow. You're shallow. Do you really want to spend $2.99 on a romance with a cover that looks like this?
Would you spend money on a book that had a cover that looked like this?
Come on. He's wearing a loin cloth! How could any woman resist that?
Point being that while the story inside may be the same, your assumptions going in and even your very decision to buy the story is based off a one second glance at the cover. So this is not something to just gloss over, even for a short story you plan on selling at 99 cents.
And on top of that, cover art can be a tax write-off. If you're making enough in sales to merit reporting it to the government, any expenses you have as a self-employed author can give you a reduction in taxes.
Note: I'm not a tax professional. You should definitely consult with yours about this.
All I want to point out is the bigger picture. Don't immediately think, "Oh there's no way I can afford a $75 cover for this story." Consider all the aspects. If you're writing the story anyway and publishing it as an ebook, it will be up for sale forever. Giving the story a professional front will increase the likelihood that someone will buy. Cover art is not just a superflous expense, it's an office supply and, therefore, a potential tax write-off. As a writer it's part of your business.