I think the art of marketing, is more important that the making of the art, that is not to say and unskilled photographer will do great if he is a great marketer, but it does embellish the thought that if you have the skill as an artist, it is imperitive to have the skill as a marketer, I currently have pretty good success at selling quite a few pieces, but the exposure came at the expence of donating quite a few pieces to auctions to raise money for a good cause, and now that has transformed over into sales from people who have seen my pieces at the auctions and requested a portfolio of my work, hence resulting in a good bit of sales.
But the ability to make a living off of art photography is difficult at best and for most a very long and thin income venture, I supplement my fine art sales quite a bit with regular stock and often a wedding or some other form of photography, the current ground glass business came about because of lackluster photography sales and the need for a screen for one of my own cameras, in which I did not have the funds to purchase. I have listed work on ebay with some success, but they are not my fine art pieces, the only thing I list on ebay for print sales has actually been posters that retail for a small amount of money, which does not pose the threat of lessing the value of the actual print.
Just my .02.
Ground Glass Specialties