The raised line coloring book I have is very simple images for preschoolers and I found it at Walmart for bout $5. I have also seen it at our local education supply store. The ones for the visually impaired are about $15. I have also taken "puff paint" to a coloring page to raise the lines. It is a lot of work and can warp the page but can be worth it. I like coloring the raised line ones with my eyes closed, focusing in really hard on the feel of the paper, the line, and the crayon or colored pencil (not a big fan of markers).Ah ha! found it...
http://www.mead.com/meadstore/catalo...p?prodId=48042

The preschool crayons that have a ball that goes in the palm of your hand and then come down to a point are worth experimenting with too. It makes it a gross motor experience rather than fine motor. OK, seems they don't have the crayons any more but they do have the markers
http://www.crayola.com/products/list...RKS&educator=0