High energy weapons and EW are the only realistic way to deal with it without slinging 100k or 2m dollar missiles around. One problem is these missiles still have debris, though less deadly than an armed drone, they can still be hazardous. Lasers and other high energy weapons are probably the most cost effective and reliable solution for sub 10 pound drones. You generally need only knock out the MEMS gyro, overheat a motor or blind its sensors.
The problem is that drones are cheap and easy to slip around defenses. The other issue is weapon system reliability... the US military expects an extraordinary amount of reliability from munitions / weapon systems and they are supposed to be near 100% reliability. When they launch a missile, it's unacceptable for the missile to not launch.
The Coyote[1] is an interesting counter UAS concept and could be much more cost effective solution.