It's a key component to any well-integrated home air defense system.

At 95% less than $250,000, why wouldn't you have one?

Have you seen the state of the world recently?

Not sure about personal usage but poor governments could save a lot on and have backups for fraction of the price.

Very handy for boats, planes, checking if Godzilla is on path for your house.

Genuinely curious why would any one need a radar.

People studying weather, the atmosphere, birds and of course people expecting aircraft. :)

This particular radar is bloody expensive, though - its price tag is about 15 000 euros.

Other fun radar projects, most of them well above my head, so I won't dare to wade in:

Henrik Forsten: home made polarimetric synthetic aperture radar drone (takes photographic quality radio images of ground, budget several kiloeuros + ability to fly or a high vantage point)

Radar Tutorial - old military guy explains all the concepts, provides many schematics and various formulas

WetterSat - Mobile amateur rain radar - helps you locate rain at 10.5 GHz within a 100 km circle, cost about 1500 euros

Daniel Kamiński's blog - explains the principles of a GPU-accelerated passive coherent location finder (radar that uses non-cooperative external illumination sources like TV signals), cost a few hundred + a high end GPU, but completeness is low (hard to recreate)

Uh, to see stuff?

It gives you time to pull on your brown pants for the incoming drone invasion.