Article doesn't mention a big audience that would be very interested in cheap book scanning: the print disabled. Blind and partially-sighted people are the most obvious members of this group but dyslexics and others who cannot read normal print would also benefit. Many books are of course already available through libraries for the blind but if you need less-popular or specialised texts you are out of luck.

With an aging population it seems this is a very natural niche.

Now if it were only OnePoundScan instead of OneDollarScan...