Try discovercircuits.com, they have tons of LED circuits. But if you want a very simple, very long lasting solution. Use a single flashing LED, and 2 batteries. The fewer components, the lower your power needs. The Flashing LED runs direct off the battery, no resistor required. Believe they are in the 2-3 Volt range, regardless of color, and flash at 2 hz... This is only the cheap and simple solution for a deterent.
Now, if your goal is to make a simulation of the actual alarm, so somebody else thinks they are protected, when actually they no longer are... hope you get caught.