I don't really worry about it much. Remember the saying, "imitation is the most sincere form of flattery". Nobody has yet made a fortune on my art work, and if somebody does, believe me, they will have me to answer to! Actually I have mugs printed with my art work, and pillow cases too. Am planning to add shawls.
I spend about 2 and a half months on each painting. I love enriching the surface, layer by layer. Happy painting to you!