I had a look at it and it looks like you can download the program for free but they're saying you'll need to host it on Yahoo servers (purchase a hosting plan). I can't imagine that you wouldn't be able to just ftp the files to your server though and skip their hosting but just don't know.
Did a little looking around and the Nvu program looks like it's worth a look though I don't know anyone using it and have never heard of it before. It's free, open source and has ftp functionality built in.