I have just completed one for no money unless to mention the labour cost of myself and my fellow colleagues were involved. Yes, some IT stuff also involved but nothing serious. It does the job from audit planning, audit management and administration till capa management including workflow management, common network authentication, etc. as well. All integrated into one integrated global kind of system.
This is the holy grail for audits and all surrounding activities, I had plan to publish a how to in general, but it's still a plan for my spare time
Look for free customizable tracking systems like trac and redmine.