This document discusses the pros and cons of building a custom application on the Force.com platform versus purchasing an application on the AppExchange. It notes that building custom apps requires significant time and money, and leaves organizations stuck supporting outdated technology. It also highlights risks like developer churn and the difficulties of development versus ongoing support. The document argues that pre-built apps from vendors incorporate expertise, best practices, testing, and ongoing upgrades and support that are difficult for custom solutions to match.