>> but any one algorithm only serves an extremely niche audience.
Forget the algorithm. They need to fix their customer service, their sales process. Customers want pixels, but they need basic services: simple and a predictable price. I want to give a location (pix+radius, four corners or whatever) and a delivery schedule (once a week etc). But when I try to buy that stuff I get package deals, "ask for a quote", and vague statements about times. That doesn't work. Normal customers, ie not intelligence agencies, don't want a drawn-out negotiation process. The first company that can provide a basic web interface for purchasing imagery quickly and piecemeal will win the market.
Top of the list for small customers are probably high-end real estate agents. They want to monitor their neighborhoods for houses that are under delayed construction or backyards/pools that are being neglected (sure signs of someone ready to sell).
Civil litigation attorneys: I want everything you have about this particular intersection. Cops: I want any images you have of this house between these dates. News agencies: There is a Russian ship on fire at X location. When can you get us an image? And a great many other small customers I cannot think of at the moment.