Iron Dome missiles cost 40,000 dollars and could cost effectively intercept Shahed drones.
Israeli Iron Beam and its airborne derivatives cost like 4$ per interception and could bankrupt Iran if it chooses to go all out on the drone route.
Israeli recon blimps can detect low flying drones from hundreds of kilometers away.
The problem is that Shahed-136 is not Qassam rocket of Hamas with its high infrared signature and predictable flight path.
Shahed-136 has low infrared signature, low radar signature, flies low, is small and difficult to intercept.....
You will need more advanced and more expensive missiles to take out Shahed-136 and since Shahed-136 costs only 20.000$, it can be produced in thousands and even tens of thousands. For example a drone factory that Iran is currently building in Russia will have a capacity of 6.000 drones per year.
Regarding Iron Beam, it is not battle tested, it is just a theory and it can evetually become a failed project just like failed US Boeing YAL-1 Airborne Laser.