Window Help

Does anybody out there in the peanut gallery have suggestions for inexpensive window treatments?

The thing I love about my new room is that it's got windows on three sides (one of 'em a big sliding glass door that goes out onto a wrap-around deck that's only accessible from this room!).

Except that since I work mostly nights, I need to find a way to block out all of that light so's I can sleep.

I'm adept enough with a sewing machine to do your basic straight seam....

Thoughts?