Space X started construction on two Starship prototypes in the month of May. SpaceX has a goal of producing two Starships every week in 2021. This would be 100 Starships built in 2021.
The estimated salary, benefits and overhead would be an estimated an average annual cost $200,000 for each SpaceX employees. This means that the 3,000 employees building Super Heavy Starships would be $600 million per year. If there were 100 Starship built each year and 20 Super Heavy Boosters, then each Starship would have about $4 million in labor and each Super Heavy booster would have about $10 million in labor. If the production rate was halved and the staff levels were the same then the labor for Starship would be $8 million and the Super Heavy booster would be $20 million. SpaceX is four times slower of the goal at the two per month construction rate. The labor for each Starship would be $16 million and the Super Heavy booster would be $40 million. SpaceX has not hired all 3000 staff at this point.
The steel is about $200 per kilogram. The dry mass of the Starship will be about 120 tons and the Super Heavy Booster will be about 300 tons. This would be $2.4 million for the Starship if most of the material was the steel alloy. The Super Heavy would be $6 million of steel.
If the steel and salaries are half of the total cost of the rockets then the unit costs at different production levels would be:
Two Starships per month would mean $37 million per Starship
One Starship per week would mean $21 million per Starship
Two Starship per week would mean $13 million per Starship