Also thinking the plastic shrink covering would be good and not nearly as pricey. When we moved to the great snow belt, even though our house had good thermal pane windows, many suggested we add this. Quick job, inexpensive, worked like a charm and you'd never know it was there as it shrinks to be nearly perfectly clear. IIRC, the brand we used was Scotch brand. Double sided tape around the frame, apply the plastic, grab the hair dryer to shrink and you're done. You still have great visability. Removal is easy but may require a smidge of Goo Gone.