The thought that came to my mind is why not build off your beta in ag to build a track record that you can then use to either advertise off of or figure out how to have current customers bring in future customers?
There may be a way to have people who are pleased with your service and the pricing they got to become your de facto sales force to bring more people on to the platform.
It would be interesting if your platform could tell people – if we could get y more orders on board we could save you x more dollars per unit and then made it super easy for them to send that to friends of theirs to join in. That may provide the incentive needed to get people to get others on to the site for you. Obviously there is probably some point of diminishing returns where people will not expend the effort but it could be a way to make your service viral.