Generate 500 words of detailed prompts designed to help a SaaS founder brainstorm and refine niche SaaS business ideas suitable for rapid MVP development.  The prompts should focus on identifying underserved markets, validating problem-solution fit, and defining a clear value proposition for a minimal viable product.  Include prompts covering market research, competitive analysis, feature prioritization, pricing strategies, and go-to-market plans.  The output should be structured as a numbered list of actionable prompts, each with a concise description and example.  Each prompt should encourage the user to think critically about the viability and potential of their SaaS idea, focusing on building a product that solves a specific problem for a clearly defined target audience.  Prioritize prompts that lead to rapid iteration and validation.  Ensure each prompt incorporates considerations for scalability, ease of development, and long-term sustainability.  The overall goal is to help the user effectively translate a vague SaaS idea into a well-defined, actionable plan for building a minimum viable product.