There are open source alternatives, but they're not really easy to work with or set up. But these tools in combination, and a good deal of time, make it possible to do without Flash:
ASDT - ActionScript Development Tool - an ActionScript editor plugin for the Eclipse platform
Ant - a build script for various languages, used to setup the Flash project.
MTASC - Open source ActionScript compiler
Eclipse - Integrated Development Environment for a variety of languages/compilers (including ActionScript/Flash through ASDT)
Swfmill - Tool for compiling resources (images, sound etc.) into Flash swf files.
Together, they're called AMES.
You can find links to them all at http://www.osflash.org, which also has a list of other open source utilities for Flash authoring without (or in combination with) Macromedia Flash.
But again, not very userfriendly yet. And any tutorials you'll find on Flash will probably be very geared towards the Macromedia development environment.