I realize this is a very old thread but I ran across it and figured others might as well.
(Notice: I am not in any way affiliated with any video hosting companies or CDNs)
If you are interested in getting some of the best video hosting on a major CDN (aka Akamai) but can't afford it...look into some of the smaller companies you can go through that offer hosting on the big boys. We are using OnStream Media's Streaming Publisher which is actually storing the video on Akamai. It works great, and their developer is working with us to set up the proper web services to give Roku the XML feeds it requires.
(Edit) Sorry, I meant to say that OnStream is charging us approximately $100/month and the content is actually on Akamai. We just go through OnStream's UI to manage our files.