Well, if I had any interest in doing this more than this one time thing, then I'd think about making a purchase. I used to mess with graphics a bunch when I moderated a a comicbook discussion board, but that was years ago. So, I don't have any real reason to spend a couple hundred on a program I'm only going to use once.
I have seen some excellent photoshopped/photochopped pictures on these message boards, so I know some people enjoy doing requests like this; and have the skills to do it much faster than I could with the skills and tools I have.
That said, I will look at Gimp and see what I can do.