I would consider reaching out to commercial scanner companies and see if they have any interest in either: integrating your service into their software or negotiating some kind of referral program for folks that buy their scanners. Same goes for advertising on forums for folks that are using DIY solutions to do a lot of scanning. You might also consider reaching out to businesses that you know do a lot of scanning of texts like this like libraries and law firms.

Just spit balling here but if the product works as well as the demo then it should be easy to start finding a few "Library Access" level customers and start to build some revenue.