You’ll need to find a copy that’s fallen off the back of a truck, but Access Economics’ Investment Monitor for the March quarter, with a comprehensive guide to new construction and investment projects, has some interesting figures that might make you see mandatory detention in a new light.

It lists a range of projects including Lend Lease’s $160 million expansion of the Macarthur Square shopping centre in NSW; the $270 million Douglas mineral sands project in Victoria; Alcan’s $1.85 billion alumina refinery expansion at Gove and the $2.5 billion Eastlink motorway in Victoria. And there’s this line: “Some of the larger projects which have changed status to under construction in the last quarter include… an immigration detention centre on Christmas Island ($336 million).”

A million here, a million there, and pretty soon you’re talking serious money.

Democrat Senator Andrew Bartlett wrote about a visit to detainees on Christmas Island on his blog last year. “The situation facing the group on Christmas Island has not got very much public attention, and of course that is the reason the government, at great public cost, took those people to Christmas Island,” he observed. “At great public cost.” At an opportunity cost of $336 million – plus everything else that’s been spent there.

The Economist’s online dictionary defines the notion of opportunity cost as “the true cost of something is what you give up to get it. This includes not only the money spent in buying (or doing) the something, but also the economic benefits that you did without because you bought (or did) that particular something and thus can no longer buy (or do) something else… Everything you do has an opportunity cost. Economics is primarily about the efficient use of scarce resources, and the notion of opportunity cost plays a crucial part in ensuring that resources are indeed being used efficiently.”

Access Economics seems to think that the Christmas Island detention centre development is serious money. Serious money invested without the dividends the other projects it lists seem to offer.

Given the way this government likes to boast about its record of economic management, couldn’t we get something better for our $336 million?