I am no expert, but I think you would need a multilayered system, these drones are flying at tree top level at most, which probably evades radar, so you need a low-level early warning system or a local area radar that only covers the surrounding area.
Then you need a repeatable low-cost way to take them out.
I was reading that Israel is testing out the Iron Beam, Laser system, that somehow has reduced the cost to fire a laser capable of taking out a drone to pennies.
Then maybe a CIWS as a last resort.
Just throwing out ideas.
Someone mentioned a cheaper, lower caliber CWIS as a possible option. I wonder if a .22 caliber lR rimfire version exists?