To help keep energy costs down this winter, consider installing a plastic barrier on windows to cut down on drafts and leaks. You can certainly buy the kits, however if you watch for sales, you can get plastic shower curtain liners for a minimal price.
It is just like layering your clothing in winter. A turtleneck under a sweater is going to keep you warmer due to the two layers. This works like that, creating another layer with the plastic shower liner. Under the curtains, it is barely noticeable, but what will be noticed is the difference in your heating bill.
Thumbtack or nail the liner in place. If it is too long, roll up the bottom and tuck it onto the window sill. You also may be able to cut the shower liner to fit two smaller windows, or just double layer the plastic.
Keep warm without breaking your budget this year!