The Pitbull Investor represents a model approach to selling a trading system: The developer gets $60 for the idea, discloses it completely and then earns some additional income after the initial sale by implementing and/or updating market calls for people, or even pulling the trigger for them. According to IMF, some 13,000 customers are currently relying on IMF for updating. Most folks just don’t have the time to trade all the gee-whiz systems they find out there; there’s a market for ongoing service, and IMF provides that.