Sharepoint Designer is now free!
Late to this game, as usual but still adding here. From: http://blogs.msdn.com/sharepoint/archive/2009/04/02/sharepoint-designer-available-as-a-free-download.aspx
Sharepoint Team made Sharepoint Designer available as a free download. I've been using SD for customizing our internal site we use to run our processes, it is invaluable tool.