Stan Collender lists the consequences of a GOP-led government shutdown:
Shutdowns actually cost the government more money ($800 million last time according to Time) than it would otherwise spend and, therefore, increase the deficit compared to what it otherwise would be. Departments and agencies have to begin to implement shutdown plans within a few days of the possibility that their appropriations might expire. At a minimum, this involves additional communications security, building maintenance needs.
2006-2011 archives for The Daily Dish, featuring Andrew Sullivan