Steven:
As wth many others who have replied to your question, I have limited experience in selling my photos. As a matter of fact, yesterday, I posted a question about pricing of photos for marketing materials.
However, I have had a litttle bit of experience (little being the operative word) in selling single images to the public. First of all, as has been the consensus, do not sell the original file. The woman has indicated to you that what she wants is a print on canvas, so work on selling her exactly that. I would explain to her that, if you sell her an original file, you have no control over how many prints are made thereafter, or to what use they will be put. Therefore, if you sell her the file, you would have to charge a fee that would be reflective of an unlimited license to use of the image. Explain further, that such an unlimited llicense would be very expensive. Tell her that you would be glad to provide the final photo that she desires; and, get particulars of the size and finish that she would like.
As for price, that just comes down to what you might feel comfortable with. I would not consider selling for less than 2 or 3 times your expense in getting and shipping the final product to her. As an example, I have sold framed prints at several venues. Like you, I was lost as to what to charge. The images were cheaply framed ($12.00 black metal frames and $7.00 to $14.00 dollar matting). I priced 11"x14" @ $115.00, and 12"x18" $150.00. As I prepared pricing labels, I thought how I would never pay that much for my images. Well, at every venue, where they have been shown, I have sold a number of each size; and, I have never heard the comment from anyone, that they would like an image, but the price was too high. So, I guess, for those images, anyway, my price guess turned out to be a reasonable figure.
Forget the thought of trying to figure an "artisitic val;ue" for your images. Until you have developed a reputation as a photographer, there is no artistic value. Until then, you are merely selling a comodity. So, price accordingly. Figure your cost, and what you feel would be a sufficient profit, to make this activity worthwhile, in your own mind.
Cliff
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Cliff
http://www.pbase.com/cliffb