Queen Mary cost £3,500,000 in 1934 (I think!)
£1.00 in 1934 = £51.70 (retail price index 2008!)
Therefore if she was built to the same spec as then - with 'best everything',
and if I have done the sums right - she would cost roundabout £180,950,000
Cunard took out a loan in 1937/8 (I think!) from the government of £5,000,000 for Queen Elizabeth
That would be £258,500,000 today
Her exact cost might well be found in Clive Harvey's good book!