As3-audio is a project mainly written in ActionScript, it's free.
Audio Management in Actionscript
h2. as3-audio
Audio Management for AS3 built on as3-signals.
h3. Overview
Audio provides an easy way to work with sounds on Actionscript 3.
h3. Syntax
var audio:IAudio = new Audio('id', 'path/to/sound.mp3');
audio.volume = .5;
audio.completed.add(onSoundComplete);
audio.play();
var audio:IAudioX = new AudioX('id', SoundClass);
audio.play();
audio.fade(1000, 1, 0); //time, to, from (optional)
h3. Some Features