Based on aerospace history, I really doubt the program can be done for $45 billion. Frankly, I doubt it can be done for $60 billion, especially if it's ran by a government agency. Government procurement regulations alone drive up program costs substancially. I also don't see the ISS budget dropping by $2.25 billion a year even after it's "finished." The O&M costs are going to be substancial. In addition, there will always be competing needs for the money, such as developing a replacement for the Shuttle as discussed here.
When it comes to agency budgets, there are always competing factions fighting for their share and some of the other department's share, too. Like making sausages, how a budget gets developed and allocated isn't pretty. I've seen these battles firsthand - squimish people need not apply.
Space/Science » in reply to Yeap, that's the number I used
I'm really skeptical of that projected cost