I’ve been following these as he releases them; just a quick warning that he’s using a $2,500 radar module that’s often backordered. It’s an awesome tutorial but definitely in “serious hobbyist” territory if you want to follow along for real.
I've built the MIT radar before and it is a great way to learn the basics of radar!
In either design you can likely get away with <$500 worth of materials.
Henrik has follow-up blogs adding and modifying this design for more functionality, it's a pretty neat project to follow!