The Department of Homeland Security's FY11 budget authority was around $56 bil. The TSA only accounted for 14% of that money. [1]
Just for perspective -- top 5 slices of DHS's FY11 pie: U.S. Customs and Border Protection (20%), U.S. Coast Guard (18%), Transportation Security Administration (14%), Federal Emergency Management Agency (12%), Immigration and Customs Enforcement (10%).
Don't get me wrong, I'm not a huge fan of the TSA... I think we all feel a little silly as grownups waiting around in a security line in our socks. But I don't think all the hand waving about "security theater" is really justified. And there are probably quite a few things that fall under "homeland security" that aren't so controversial. Disaster response? Maritime search and rescue? Enforcement of fisheries conservation regulations? Border protection?
[1] All numbers from DHS's "FY 2011 Budget in Brief"