Boldly going. Awesome concept; however, a $1T, 85 million kg. ship is not realistic.
What could we do? A saucer is just not a good shape for space but we can keep the three cylinders.
A BA330 is 23mt for $100m. But a Falcon Heavy will lift 53mt and so let's get Bigelow to make a 40mt BA700 with life support for 21 for $180m? There's no technical difficulty here because Bigelow has shown their designs to be very scalable (see the 70 mt. BA2100.) Putting three in orbit cost $900m. giving you redundancy and tethered together you get artificial gravity. You get three used FH upper stages for free to provide propulsion. Total dry ship mass of about 200mt. Add to that one red Dragon (5mt. and $50m each) for every seven crew. A crew of 63 would require 9 so our ship now has a mass of 250mt and cost $1.5b.
That's $24m per crew which is amortized over the number of ship missions. Fuel cost is per mission.
How much fuel depends on the mission but let's say 2,400mt. for a mars mission. This gives you a fuel cost of $3.6b. Definitely an incentive for a LEO fuel market.
...and that's the whole point!
That's $81m per person for 63 people to the martian surface for under $6b. That would show a commitment to the success of a martian colony. I wish Robert Zubrin and/or Elon Musk would provide details on how you get that down to $500k per person.
Power Update: 100kw and 1.2mt.
Now you know why bud light cans work...
Nitrogen is the reaction mass.