I think it depends.  Any item is worth what someone is willing to pay for it. I sold an image file for $500 USD and it was only a so so image if that as far as I was concerned but it was useful to the person who wanted to use it for an advertisement that ran for 2 weeks in a political ad.  I have sold a few prints in the $180-$250 range that were much more pleasing to the eye but even they were not what I would call award winning images.

This is the image that sold for $500 (I think it is a very mediocre image at best and was shocked when an agent contacted me much less paid me $500 for it out of the blue.):

The ones I donated for a charity auction sales were a lot nicer and were sold for significantly less.  One was a black and white of fingers on a violin finger board, another was a country farm scene and another was a steam train in black and white.  None were what I would really consider great images but they were of a higher standard than the above snapshot taken at West Point.

More money is typically made through commissioned works than through print or stock sales in general since there is a contract before the work is done.

Where would you go to sell you pictures, though?  I put a few on a site last yr but nowt came of it.

Elizabeth

-Steve...It goes without saying that someone has to want the picture...that point is obvious which is why I didn't need to state it.

I forgot to mention that the image of "Duty Honor Country" was not up for sale and it was not being marketed...none of my images are marketed...it just appeared on my blog site and an ad agency stumbled upon it via a google search and contacted me through my site.  I even asked the agent why he didn't use a stock site and he told me that there were too many images and the google search was quicker and easier than wading through the stock sites.  So you just never know.

I had dabbled in doing the pro tog thing and did have a small but reliable client base...well up until the economy tanked and the influx of "pros" that the digital age has created. One fairly large client also found me through a simple google search.  They saw an image of their campus...it was a University...and contracted me on several occasions to do work for them.  The other clients I had were people I knew and contacts through people I knew.  I didn't make a lot of money, really only enough to maintain my camera gear and a few upgrades...lol. 

In 2009 Time Magazine used an image for a cover that they only paid $30 for it through my stock photo (http://www.mediaite.com/print/times-30-cover-photo-cheap-now-expensive-l...) In the past images that made the cover of Time normally earned thousands, anywhere from $3000 to $10,000 but that photographer got $30 and a cover image on Time...which could be said was it's own reward to that particular photographer.  This is what the industry has turned into. 

what would the average worth of winning pictures be, in the commercial sense, like it was put up for sale?

£0.03 +VAT LOL

Seriously though, it's worth no more or less than a none winning picture. Which on average, is virtually nothing. What is chosen as the winner in the comps here, is based on one or two peoples personal choice, as selected judges for the comp. That adds nothing to its monetary value. All images have zero monetary value, until someone is willing to pay for a copy, or the sole rights to it. And even when you get someone interested in buying, you've usually done hours of donkey work, getting it to that stage. So your hourly rate from the sales net profit, is likely to be less than you'd get delivering papers on a morning