You really want something that becomes turned off once the capacitor charges up, correct?
Yes, I would.
I really wouldn't like to have DC Source like a battery powering the buzzer. since its merely for the few seconds. wouldnt charging up a capacitor do?
I would really appreciate if you could draw up the schematic for the circuit you mentioned when you get time to do it.
Thanks in advance. 
Seems like my simple circuit keeps growing bigger :-/