You should take a look at InstallJammer. Not only is it free, it's cross-platform and very easy to use. Most common actions don't require any scripting at all, but with a powerful scripting language underneath the hood, you can make an install do just about anything you want.
If all you want is a basic installer to install your application, you can have it built in a matter of minutes from the first time you start it up. If you want something more powerful, the capabilities and documentation are excellent.
