4 rockets to destroy an Armored Door. That's 5,600 sulfur in raw materials.
2 C4 charges to break an Armored Door, roughly 4,400 sulfur plus metal fragments and tech trash.
12 satchels to destroy an Armored Door in Rust.
The cheapest explosive option for an Armored Door is 2× C4 at roughly 4,400 sulfur.