Hi, Beverly;
What you can do is find similiar artists, click on "Art Prints" then side the price, click on "Show Price Details." You can go through the different sizes and see what folks charge. FAA will add a $5 fee on those prices. It looks like you're a little low to me. I charge more for photography than you do for your art when I would think it should at least be more even, even not a little more for art. On cards, I charge for a 5X7 print except in caseswhere I have made it an actual card and market it that way.