De Flash is the lowest priced swf decompiler available.

Tucson, 10 April 2003 - 19.5 Degrees launched a new swf decompiler which has capability of extracting action script, mp3, images and vector graphics from swf file of version 4, 5 and 6 and even compressed and protected swf. For more details, go to http://www.19.5degs.com/worktunnel/deflash.php