Gift ideas for a terminally ill child (see details)

I’m looking for simple gift ideas for a young boy with cancer. I should add that I’ve never met him or his family in person, but I have been following his story for years now and I have been in contact with his mother online. I have donated money a few times but I want to do something more… he’s 5 years old so a toy will probably make him a lot happier than money will. I just want to give him something to take his mind off things. Any (fairly inexpensive) ideas??