Instead of marketing to a general audience, I'd approach the people who really might need something like this: owners of vehicle fleets (haulage trucks, rental

Instead of marketing to a general audience, I'd approach the people who really might need something like this: owners of vehicle fleets (haulage trucks, rental cars), and companies that send their workers out on the road (consultancies, sales). In other words: B2B rather than B2C. The app could be tailored to any of those particular markets (and relaunched under different names, if necessary). If there's any existing competition, then you know you're onto something! Lastly, re-examine how other 'receipt' apps do their data entry. IMO, it's easier for the user to photograph a till receipt or fuel pump meter readout and have the system magically convert that into data.