Flash is not just an animation tool, which many people automatically assume it is.
It is (arguably) a complete production environment with its own programming language and the ability to interact with dynamic data sources and video.
If you want some animations then SWiSH and KoolMoves are fine and, as you say, they cost comparatively little.
If you want a rish development environment where anything from interactive CD ROMs to dynamic web applications can be programmed, Flash offers more than anything else currently available, unless of course you get into Macromedia Director territory which is even more expensive (and a lot scarier).
Flash was never meant as an out and out animation tool - its development capabilities have been badly overlooked for a long time and the last two versions have done a lot to redress that situation.
This falls down to one of those "right tool for the job" scenarios. Pay less for something that works fine within its limitations. The moment you begin challenging those boundaries you will start to lean towards Flash again.