What is a cheap but somewhat attractive window treatment for a large office window?

I just changed jobs and have an office now. The window is probably about 6 feet high and 8 feet across (it’s actually a double window). The top of the window goes all the way up to the ceiling. There’s a ventian blind that’s pulled all the way up, but I won’t put it down because the view of the city is great.

I want to put up something like a valance or some kind of window treatment. I am crafty and can do a lot of things with fabric, ribbons, etc. I don’t want to spend too much, as this office might only be mine for a year or two.

I can save money by not using a rod, and attaching the treatment to hooks, velcro, the top of the blinds, or some other way. If I could keep the cost below $50 that would be great.

Any suggestions?