3 rockets to destroy a Garage Door. That's 4,200 sulfur in raw materials.
2 C4 charges to break a Garage Door — roughly 4,400 sulfur plus metal fragments and tech trash.
9 satchels to destroy a Garage Door in Rust. Satchels have the best damage-per-sulfur ratio on soft sides.
The cheapest explosive option for a Garage Door is 42× Beancan Grenade at roughly 2,520 sulfur.