I think the best place to start is with the source.
www.thomaskinkade.com I purchased my canvases at a Thomas Kinkade Gallery (they have them all over the country). When we were in Disney this summer I saw for the first time a print of the New Day At Cinderella Castle, it was small, about 8 x 10 for about $15 I think. I haven't seen prints of any of the others in person. Many if not all of the images are available on paper or canvas, the paper still being a limited edition, but less expensive than the canvas. There are prices on the Kinkade website for images that are not sold out to give you an idea. There are also different editions, some being more expensive than others. As an estimate, the smallest canvas (12 x 18) in the s/n (standard numbered edition) are about $750. Same size in the g/p (gallery proof edition) is about $900. Also, once an image is sold out, the price goes up. Now is a good time to start collecting because only 4 out of the 12 images in the Disney Dreams Collection have been released.
1 - Snow White Discovers the Cottage (Aug 2008)
2 - Pinocchio Wishes Upon A Star (Feb 2009)
3 - Tinker Bell And Peter Pan Fly To Neverland (June 2009)
4 - Cinderella Wishes Upon A Dream (Sept 2009)
Also there are the 2 images that came out before the series started that are Disney related.
Disneyland 50th Anniversary (Sept 2005)
A New Day at the Cinderella Castle (Oct 2007)
Can you tell I'm a huge fan of this collection?!?! Best of luck if you decide to start collecting. The canvases are pricey, but so beautiful in person, you won't be disappointed! The Castle is my favorite piece, and the first one I purchased. I have a BIG canvas of that one, but the smallest canvas size of the 4 in the Disney Dreams Collection. (Some were part of a wedding gift from my parents, we aren't ridiculously wealthy, haha.) Didn't go for the Disneyland one because we have never even been to Disneyland. Trying to budget to keep up with the collection in the future. They are said to release 2 a year, although Cinderella came out a little early. Hope this helps!