Building a cheap helicopter is a complex endeavor that typically involves significant costs, often starting around $20,000 to $30,000, which may not guarantee safety. Many participants in the discussion highlight that while kits exist for building small aircraft, the engineering and regulatory challenges are substantial. Autogyros are mentioned as a more accessible alternative, offering safety advantages during engine failure, but they still require a solid understanding of aerodynamics. The conversation emphasizes that building a helicopter is not as simple as welding parts together, and thorough research and experience are crucial. Overall, while DIY projects are appealing, they come with serious considerations regarding safety and legality.