a post with "It is a cliche, tired and worn, that one has to remind new writers that magic must have a price."
My knee is quick to jerk about any statement that's so broadly unqualified. Surely, there must be some exception, some time when magic does not have a price. Maybe the price varies depending upon how you define price. And it depends upon how you define magic.
Let's suppose you define magic along the lines of many Grimm's fairy tales. For instance, you can get these magic powers if you sell your soul to the devil. (If you do, hire Daniel Webster, my Whig hero to defend you.) Another example of this sort of magic is one where you can do magical tasks, but each time you do someone drowns a kitten. This is a common approach in some stories including magic. Let's call this Aladdin-style magic.
One thing I have noticed about Aladdin-style magic is that it depends upon a mortal making some deal with some angel, demon, devil, or deity to get that supernatural being to do stuff. Hence the price of Aladdin-style magic is a matter of bartering with the supernatural being.
It also requires some cleverness on the part of the magic-user to prevent the supernatural being from becoming annoyed and squashing your hero like a bug.
Then I started to think more broadly and I found reasons to think that magic might not have a price. But I realized I was thinking of a different sort of magic. Something more procedural in nature like Harry Potter. Or better, think of the magic in Rick Cook's Wizardry novels. One needn't have any special powers, just the knowledge and intelligence to master certain abstruse studies. Let's call this Alchemical-style magic.
If I run a perl script, there's a few electrons that move around differently, some ones and zeroes change, and the electric bill is some quantum higher, but all told, that's too cheap to account for. If you want to make the case for magic that doesn't pay a price, then start with Alchemical-style magic and liken it to running software. And ignore the magical-utility bill.
But if you persist in saying that ALL magic has a price and you think the price is much more significant than a mere magical-utility bill, then consider again the technological world. The expense of custom-made software is my time and what's rare is my expertise. Sadly, while others were fitting themselves for high elected office (smoking dope and cheating on tests) I was studying mathematics and computer science. Tuition was expensive then and it's much worse now.
My daughter drew a large tick on the back of her last bill from Sally Mae, and that image COULD fit nicely into a wizard's apprentice tale.
If I ended now, I suppose Sarah was right that all magic has a price. But it depends upon how you set up your world's rules of magic. And if you're dealing with Alchemical-magic, the price varies with one's skill set. Perhaps a very highly skilled mage can perform much more powerful magical tasks with much less effort than a low-skill mage. That fits with the technology analogue.
One would expect that if all magic has a price, the creative author could figure out ways for the price to go way down. It really is up to you. You can do anything you want when setting up how your story's magic works, except be half-baked about it. Think through how magic works as a system itself without regard to the needs of your story.
Always make the story fit your world-building, never make your world-building fit your story.