I would not monetize this idea at first. I feel your platform needs to be able to provide this service prior to trying to charge companies to list their services. I feel this way for two reason, I as a customer would not trust the platform as I would believe that it only exists to pressure me to contract the services of the companies that paid to be there. I as a company would not want to put my company's reputation at risk prior to the platform having a good reputation on the market.