Sooooo... how much is a story worth?
I mean, when you get a short story (or any similar work) published, you have to expect some sort of compensation from the publisher. It's your story, after all. Unless you're actually paying that person or company to print your stuff, you have to expect something in exchange for your blood, toil, tears and sweat.
I've noticed that most publishers nowadays offer a per-word or a per-page rate -- or at the very least, some amount that can be calculated from the technical specifications of the work in question. Despite the fact that this does hold a certain sense, it doesn't address the question of literary skill or aesthetic value; By this method, you'd get the same payment in return for a literary masterpiece as you would a random assortment of words. (This is assuming that you manage to find someone willing to buy that random assortment of words, of course.)
In addition, there's also the question of exactly how much people would pay on a per-word or a per-page basis. Local publishers seem to offer extremely low rates in this regard -- the lowest I've seen being offered around here has been along the tune of five centavos (about 0.001 US dollars) per word. There also seems to be a lot of talk about companies that offer one peso (about 0.02 US dollars) per word, but this level of compensation sounds pretty unrealistic for a local publisher; I have yet to find any publications with such offers.
At any rate, I tend to get the equivalent of anywhere from 300 to 500 pesos for my short stories nowadays. This may not reflect the common trend out there, though; I may just be asking for less than my writing is actually worth.
There's also the odd publication or venture out there that offers a flat rate for writers' works. This is usually the case with serials or low-level anthologies, both of which tend to require a high number of submissions. If this is the case, then the flat rate usually doesn't amount to much (because there are plenty of submissions anyway), and not much attention gets given to the redeemability of the pieces in question (because the readers usually aren't very picky here). A good anthology in this category may end up paying better than the standard per-word rate, but you run the risk of your work getting lumped together with stuff of dubious quality.
One interesting practice with regards to compensation involves giving the writer some copies of the resulting publication. This is usually a pretty good deal when you're working with formal literary collections or high-level magazines: The copies usually add up to a significant retail amount, and most of us would probably admit that we'd have bought them on our own anyway. The catch is that only very specific ventures can do this sort of thing -- small publications don't have much worth in terms of retail to work with, and you'll probably want something more in the vein of financial payment from the more established companies.
Finally, there's the more romantic, idealist approach, where you give your story away without expecting any form of compensation at all. There's nothing wrong with this, mind you: I think that such idealism should be admired. However, I do think that giving away such "freebies" tends to be bad in the long run, if only because it seems to encourage literary devaluation. A publisher who doesn't pay for his writings tends to be more careless with them; The way I see it, if someone's willing to give me money or stuff for my work, then I'll know that there are far less chances of that person letting it go to waste.
Then again, if I had a choice, I wouldn't recommend any of these practices at all. The last time anyone asked me what I wanted in exchange for a certain piece of writing, I just asked for a nice dinner somewhere. That way, I figure that not only do you get to choose a place that will almost certainly give you your money's (er... story's) worth, but if your partner turns out to be a great conversationalist, then you'll definitely have a nice evening coming.