Here is the buzzer assy. Part# 25640-7S200
BUZZER ASM :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com
$45 here and fixed my issue, I was having the same difficulties, a light on with nothing else happening. Thanks for the assistance.
Additioanlly, the Radio Shack one was not even loud enough to hear over my exaust, but thanks for the recommendation, I did try it. At Nissian this part is about $70 or more. So $45 is not bad.
Hope this helps.