I like the idea of generating an image and selling it as a t-shirt but you have to do better than this.

Website design is not very appealing. Have a look what other people do: http://dribbble.com/

Your LurePets are not a new idea. Zazzle is selling them already: http://www.zazzle.com/lurepets+gifts . Personally I like fractal t-shirts more: http://www.zazzle.com/fractal+tshirts

But don't give up. It's a good idea that needs better front-end and more advanced math and pattern generation at the back-end. If you auto-generate images that no one else has and are appealing then you might have a sustainable business.