http://news.yahoo.com/ap-impact-foreign-insects-diseases-got-us-070735077.html Seems the real cost of actions by DHS are far more costly and damaging than known terrorist acts.
Regarding the loss of freedom the NYT has a lawsuit pending against the justice department for not revealing the secret rules and regulations for features in the Patriot Act. PDF link.
The real cost of DHS is incalculable. The loss of Constitutional rights, lost revenue to the travel and tourism industry, damage to small and mid-size businesses targeted for harassment, cost of various DHS programs absorbed by the budgets of state agencies and local municipalities... It just goes on and on. Money, time, manpower, revenue and quality of life are all being drained away by the DHS.
Along the same lines is this great paper co-authored by one of my heroes, John Mueller, of OSU. http://polisci.osu.edu/faculty/jmueller/MID11TSM.PDF It even addresses the increase in auto fatalities, Bart, as a result of people choosing to avoid airports.