Keep the heat and light out of my room. Costs/Options?

There are inexpensive window tinting rolls available at Wal-Mart in the automotive section that you can also use for the home. We tried them and found them to be very effective. Also, you could find some room-darkening mini-blinds at Home Depot, and they work a lot better than we ever imagined they would. Top the blinds with some dark-colored dries (with or without backing material) and you should be good to go. The blinds are reasonably priced, and the temporary ones are cheap and very effective. If you're at your wits end, you could paint the window. Just don't go the tin foil route!