That number was based on full occupancy. The barge is currently well under that full occupancy.£75k per person (roy's number} seems about right, based on your number its just under £45k. it costs £40k per year to house a convicted/remand prisoner. Now our resident human rights campaigners would be the first to complain if the standard of accommodation was worse than a prison. It also had to be stood up at incredibly short notice.
The £75,000 per person is also comparable to a hotel room, if paying nightly. A full two years cost would be well below that, especialy if paid in bulk, and for numerous places, like a framework contract.
So the barge is not value for money.