I’m not too familiar with Cafepress…have you tried coloring in prisma markers?
I think even if you scan in your images at a high resolution and they “look funny” all those tiny details won’t ALL show up once they get printed on things-especially if they are printed on smaller things like tote bags or mugs. And too, probably the details you don’t want, will get lost in the printing process. I hear Cafepress has some high quality items, but I doubt you’d be able to see brush strokes. ❓ Sorry I couldn’t be of more help