What's the business model? I could, for example, design and make an open source controller board suitable for a microwave oven. But how do I sell microwave ove

What's the business model? I could, for example, design and make an open source controller board suitable for a microwave oven. But how do I sell microwave ovens competing on price with people who have been building microwave ovens for decades and have basically perfected the art? How do I stop companies in China from taking my controller design and selling it at half the price?