This is one of the more organized site ideas I've seen for selling a service.
Plenty of examples and decent artwork throughout (although I question the statement "We don't use computer effects to create your artwork". You should have merely stated that "No completely automated computer renditions, all work is done individually by skilled artist". This would be a bit more accurate.
The english used in describing the services needs some work, for example:
"We are so confident that you will adore your Uniquepopart artwork that we support up all our products with our absolute no questions ask money back guarantee."
It would also be better to describe your site when referring to it as "Unique Pop Art" instead of using the web site address.
This example is prevalent throughout your website. Someone with a better understanding of the English language would be of great benefit to your site. As mentioned earlier, site navigation is good.
To have a professional looking site with less than proper english diminishes the site. Once your ads are read, no matter how organized it is, without proper English wording it changes the perception.
Although the artwork is not the best I've ever seen, it most certainly is not the worst. The idea of someone sending in their favorite photographs and then converting them to canvas, to me, is more important than doing artwork to impress someone other than the client. The ability to place the images on a canvas is a huge factor in selling your idea. Clean things up on the wording and I think you'll do just fine.