Cocoa

Here’s a topic I’m completely ignorant of – Mac OS X programming. I used to have Code Warrior for my OS 7/8.5 machine which I used for both Java and Mac C++ with the PowerPlant framework. Is there a free Cocoa based development environment for OS X? I’ve installed the Mac development tools, and have set up a cross compiler for the Zaurus. I’d like to get set up to do Zaurus programming, Mac programming, etc on that box. If I download some stuff from Apple, can I program Cocoa GUI tools without paying $800 for Code Warrior?