So, I recently hacked some window coverings into the window that I found in a dumpster. They were these large pieces of white styrofoam that I found in a dumpster. I managed to fix the pieces into the window that only had those tinny aluminum mini-blinds. My wife complained at first, but it was an improvement, and kept the heat out rather effectively.
We did end up getting curtains, and moved those pieces of styrofoam into the attic/crawl space to work as additional insulation. Now everybody is happy.