horn location

My sister has a 96 protege with a horn that sounds muffled. It barely makes any noise at all. Is this a common problem? I need to know where it is located and if it is hard to reach. I want to replace it with an after market horn. A Mazda service center told her they could replace it for $100. Is this the usual price for a horn? I would rather replace it myself and save her the expense.
Thanks,
ecnar

The relay for the horn is behind the passenger side kickplate or what ever you call the side trim in front of the door.
The horns are behind the bumper just center of the lights.
Typical price on ebay for used horns is $10 and a new after market is ~ $33.00. You can probably find one at an auto store for about the same price.