Photography can be valued as either art or commerce, and each transaction is affected by its own market forces.
The value of a piece of art is defined simply by what someone is willing to pay for it. That explains why a photograph of the inside of a 99 Cent Store fetched over three million dollars at auction. Beauty is, obviously, in the eye of the beholder.
It is unimaginable that an image created for marketing, advertising, etc. — commerce — would generate enough value to merit such a stratospheric sum, yet images used in commerce bring benefits beyond "beauty." So, how might a value be assigned or determined in the realm of commerce if not by the yardstick of "eye of the beholder?"
Fortunately, some guidance in equating an image's value can be found in the realm of advertising.
Specifically, magazines have, over time and based on many factors, including the number of readers, the characteristics and qualifications of those readers, and the perhaps intangible reputation of the publication, established rates for presenting a message to those readers. They spell out that exchange rate — so many Dollars (or Euros or Yen or Reals) from you for so much area in an issue for you — in what is usually called a rate card or media kit.
If you can provide a magazine with a high-quality image and they display that image in support of their editorial mission, though, you are essentially substituting a different thing of value — an image that is useful to them — for something that benefits you — an image of your product or location or service appearing in front of people in your industry. It is that exchange about which I contend we can equate the value of that image to an ad of comparable size.
Number, Numbers
(Note: in a previous version of this article I listed prices down to the dollar. For the sake of not dragging us through those weeds, I will round the figures to simpler ones, and also reduce the sheer number of examples. Enjoy.)
Here are some rates for full-page ads in pan-aerospace publications, like Aviation International News (but without naming names): $9,000, $16,000, and $27,000. Those are some heavy-hitting publications with large readerships and they charge accordingly.
In mostly-fixed-wing publications, like AOPA Pilot, exemplar rates run $5,000, $10,000, and $24,000.
And on a smaller scale, audience-wise, is the niche of rotary-wing publications, like Vertical: $5,000, $7,000, and $8,500.
That is quite a range, yes, but no matter the outlet, the return is substantial. (Magazines sell ad space in smaller sizes, too, though their prices don't fall as rapidly as do their sizes.)
But, But
You might raise a finger and protest, "But if I placed an ad, I can have my headline and body copy to tell my story!"
Fair enough, as long as you also admit you will first need to account for the conceptualizing, the writing, and the designing of the ad, plus fitting it for the individual magazine (why aren't all the magazines the same size!?!). So, good for you — you have thought strategically and then made the tactical investment of having an ad created. But, don't forget, you will still need a photo, and you'll want it to be a good one.
Here's yet another factor to factor into your factorings: compared to a photograph in an ad, one that appears in the editorial milieu of a magazine is naturally viewed as more credible.
Advertising is understood to be your company making its pitch, whereas your product or facility or service appearing amidst the editorial content carries with it a greater sense of neutrality. No, you don't get to say your words, but your ad would be facing a gimlet-eyed viewer gauging those words in the light of your self-interests. A non-ad photo? Not so much.
So, yes to advertising (because, no, just because you built it (your widget) does not mean they will come), but you can get good mileage (AKA ROI) from high-quality photography that meets a magazines other needs.
What Else?
What if you could get an even premiumer (I made up that word) position? What about the front cover? You know … the cover! The location that every reader (and passerby) sees. The cover that is flaunted and advertised by the publication itself?
How might you get on the cover, and what might that be worth?
The surest path to a shot at appearing on the cover is to have a story worth telling and the photography to support it. If you have just the story, the magazine might use it. But unless you have a great photo — a great photo — that story will not be on the cover. (I've covered the topic of what makes a great cover image in two articles — Is It Cover-Worthy Part 1 and Is It Coverworthy Part 2. Why two different spellings for Cover-Worthy/Coverworthy? I dunno…)
As for figuring the value of a cover shot, few publications make the outside front cover purchasable, but some do. One publication, not included above, sells its outside front cover for nearly 40 percent higher than a full-page ad inside the magazine. Another pub (that is among the magazines surveyed above) more than triples its standard full-page ad rate! Talk about piling up the ROI…?
Of course, as with other marketing efforts, great photography requires planning and effort and skill, and that means expense. How we’ve come to expect photography to be free is a discussion all its own, but as a photographer who has spent countless hours peering through a camera, I can confidently state that great photography is anything but easy to create. Yet the most efficient and effective way of acquiring a great photo for the cover of a magazine is to have it shot on purpose.
Plus, there’s the bonus of that accrues when you conduct a photo shoot: you’ll have additional resources, many photos, to use on your web site, in social media, at trade shows, in press releases, in collateral and advertising. It is an investment more lasting than almost any other bespoke creation; great images will pay dividends for years and years. (For instance, I have a client who still occasionally turns to photography I shot for them over a decade ago.)

The old saw is, a picture is worth a thousand words. It can also be worth many thousands of dollars.