GPS-denied Nvagation system

Hello, my name is Matthew. I am currently developing a GPS-denied navigation system for ArduPilot. I am currently shooting for a 3-5 meter accuracy over the course of a half hour, and at a sub $800 price point (yes, I am aware that this is ambitious)( yes, this hasn’t been done before). I wanted to better understand what people’s needs and wants would be if this system were brought to life in a product. Any feedback would be appreciated. The complete design I am keeping fairly fluid to pull in new ideas. Thank you for your time and consideration.

Matthew