Elon Musk’s plans to send man to the red planet, Mars was never new. The SpaceX CEO answered the most interesting question on twitter, a user asked Musk the estimated costs for a ticket to Mars.
To which Musk replied stating costs will vary with the volume. He added that the costs for moving to Mars one day would be below US$ 500,000 or maybe even lesser than US$ 100,000 including a return ticket if things don’t work out.

No one knows how Elon Musk arrived at that figure, but what we know is that SpaceX have plans to settle 100 people in Mars at a time in their spaceship called “Starship”, which will be cheaper than the Falcon 9 rocket that SpaceX uses to launch satellites into the orbit.
SpaceX currently charges about US$ 62 million for one launch of the Falcon 9, which can carry a payload of 25 tons into low-Earth orbit. However if they’d use the Starship the same thing could costs 10 times cheaper.

The Starship is designed to carry 100 people plus 100 tons of supplies at the same time. The Starship’s full reusability would just limit costs to refuelling. Building of the parts with low costs stainless steel alloys instead of carbon fiber, allows it to carry more cargo at a time.
The costs for carbon fiber per kilogram goes upto US$ 200 but stainless steel barely costs US$ 3. There is a 66 times difference here, that is why Musk is pushing for a design shift in order to use stainless steel.

The engine of the eighteen level starship would be powered by Raptor engines, that’s equivalent to six truck engines. However thirty-one raptor engines would power the twenty-two story boosters. Making it super heavy.