I agree...
I grew up in artist communities, and there are a few way we handled this in galleries. In high end galleries, we had security who could watch for cameras, and people would be arrested, and fined for taking photos. But, there was a photography booth set up where one could request a photo shoot on specific pieces.

In smaller privately owned galleries, we would have cards with the artists info on them, and if someone wanted to take a photo, we would give them a card (like the post cards with an image on the front) which listed the requirements under copyright for any posting, articles or general use of the photos they took. This always included giving the artist full credit for their work, and contact info for the artist, and now would include the artists website.

Because art lovers come in all classes, we would do prints, postcards...but the best sellers are always books. You can upload photos of your art to sites like blurb.com (there are quite a few these days) securely, and actually design your own small book. They will print for you in small Qtys, and ship them to you. This allows people to purchase at an affordable price, and promotes you as most people love to show others these books.

Being in retail for over 30 years, what I have found is that people will purchase an art book for the price they would pay for a meal, without blinking...so two sizes are good. One with a few select images, your bio, and personal notes on the art included, for say 25.00. And another with a more extensive collection and more info, personal thoughts etc...for 50.00

Gallery issues aside, you will then get people like timeshiftarts and myself. I am a metalsmith, leather worker, beader etc...My current passion is learning pyrography on leather. I apprenticed for many years to learn the skills I have, but unfortunately drawing I have not learned well. I was able to take some basic art courses, but metalwork alone takes years to learn, so I had to choose where to invest my time.

Now, learning pyrography, I have found 2 artists who have graciously allowed me to hand burn their art, onto my journals. Each asks for a small fee per drawing, and full credit with links to their work, included in the description of my piece. I am very grateful to them, because I cannot draw people to save my life ;)

So...adding something, like , "If you would like to use my art in any other form, please contact me. Mass producing is Not allowed, Royalties will be required for items sold which include my art."
Or something along those lines. It leaves the door open to other artists to ask your permission, and scares off those who don't get it.