SANS published its 2005 Information Security Salary & Career Advancement Survey. The results indicate that security administrators earn an average of $75,275 per year in the United States with an annual raise of 2.9%. The raise factor just barely tries to keep up with yearly inflation (which is now at 3.4%).
The results also indicate that larger companies pay more than smaller companies and that more experience equates to more pay -- but if companies don't keep pay rates in step with cost of living increases then the only sure way to increase your pay is to switch jobs.
I knew one administrator who switched jobs every couple of years -- not because he didn't like his current job but because by doing so he moved up the payscale ladder quicker. Last I heard he was the vice president of a company in New England.
Of course that route isn't for everybody.