My sketches are always so.. Messy!
This is one of my more cleaner sketches. otherwise it'd be a mess of angles, wires and lines.

This is a sketch state I would say would be ready for line art.
Though, I wouldn't mind selling line art alone.
I'll post some up when I do some cause before the colors it looks like a real black and white lino print. (but kinda hard to distinguish the shapes through the black and white lines..