I've been using that plastic stuff from Home Depot for 3 years now. I received a quote recently to replace my basement windows with double-paned windows. It will cost about $1200. According to the window guy, they pay for themselves in 3 years.
There are sereval things that will help. The degree in which they help is usually on par with the cost.
Start with making sure there are no gaps/leaks that will let wind through. Once that is done you are left with surface of single pane glass that are very inefficient, but at least there is no draft.
Now you could put shutters on the outside of solid wood, which will help some. Better are stormwindows. Make sure you have some kind of weatherstrips between the storm windows and the old windows so no wind will come in. Now you have two layers of glass which will not be as efficient as real insulated glass but it's not bad as the air between the windows will still act as an inulating buffer zone.
Best would be storm windows that have insulated glass in them that you screw on the old windows with weatherstriping in between. Expensive option though and most people would then just go for new windows instead. I can still imagien this option if you have a historic home with the old fashioned windows that slide up. If you want to keep those since they are original to the house this might still be an option in the winter.
Finally, if there are some windows in the house that you feel you do not use anyway, or rarely, like some basement windows, you could buy some sheets of rigid foam insulation and wedge those in the windows. that will give those areas a great R value.
Basement windows can be fairly easily replaced by yourself using those glass bricks you see more and more. They insulate good and no burglar will try and get through those. If you do it yourself it'll be a whole lot cheaper than replacement windows.
If they are double hung windows, replacement sash is cheaper than replacing the entire window, and the ones I have used come with channels that the sash slide up and down in that add a lot of tightness to the entire assembly. They made a noticable difference in our house. http://www.thewindowman.com/sashkits.htm
Bascially they have older windows that could use replacing (which are expensive). In the interim what are the solutions to block Old Man Winter?
Some cheap things I've done with some success:
If the weather stripping is old and/or cheap, be sure to replace that. And get the best weather stripping you can find. I personally like the firm thin (aprox 2mm think by 1cm wide) stuff, that looks a bit like grooved extra firm foam (but I think is actually a rubber, vs a foam per se). The idea being, you want something that makes a TIGHT seal. Because the tighter the seal, the less air that will get through.
You will want the windows to latch very tight. So if the window latches don't do that, replace them or adjust them so that your window does latch tightly. And new (firm) weather stripping (above) can also help in this area. For example, extra think and/or firm weather stripping on the windows, means that you actually have to push moderately hard when you latch, which means that the seal is that much tighter (when the windows are closed and latched). Remember, the goal is to have a tight seal, so that air has trouble sneaking in.
And the obvious corollary to that, is to make sure that all your windows are actually "latched", and not just "shut". It's amazing how much difference (in air drafts) there can be between windows that are just pushed "shut", and ones that are actually "latched" (and therefor wedged shut firm against the weather stripping).
I noticed that the seals on our storm windows weren't anywhere near as good as the seals on our main windows. So I took a little tape, and taped over any of the cracks along the (inside) edges of the shut storm windows. This cut down on the drafts past the storm window (actually the small gap between the storm window and its track), which helped lower the heat loss on the primary (interior) window (because the less that gets past the storm window, the less that even has a chance to fight against the main window)!
And sometimes when people frame in a window, they don't bother to insulate around that frame (which was true, in the past, of many of our window frames). So if you can get access to the area where the frame meets the wall, consider squirting a little caulk (silicone caulk works well) and/or expanding foam insulation into those cracks. It's amazing how much that can help! Because a poorly insulated window frame can sometimes be more drafty than the windows themselves. And while you likely won't see this (often it's covered over with molding and/or drywall, it can still be an all too good area for the cold to come in...
And yes, that cheap plastic window film really can help (but can be a minor PITA to put up every fall, and take down in the spring). What the film does, is essentially give you one more air gap (i.e. a very thin extra "window") on the inside. This "extra window" (the extra air gap) does give the window system a little more total insulating ability. So if you need the extra warmth, by all means do so (because it's certainly a cheap, albeit a temporary, "fix"). FWIW: I currently do use the film, but only on a fraction of our windows (and only after I've done all the other tricks, above, and still want more warmth at that particular Window).
If you want to really do it on the cheap, for areas of the house that are rerely used (basement, etc), you can cut cardboard and put it in the windows or make a quick curtain using a wool blanket. either of these can be hung up tied up or removed during the daytime, or when light is needed.
i live in south florida. we have the opposite problem with efficiency. down here its a battle to keep cool in and heat out. what misty fies me is how houses are built today with 2 or even 4 windows per room. why is this? i guess it is for natural lighting. but its FAR cheaper to have 1 window, or better yet no windows, and just use light bulbs during the day.
think about it, would you rather pay to run a light bulb or pay to run the air conditioner, or heater (for you northern guys).
so based on this idea, i went looking for the best insulation i could find. and i found it in the form of 4x8 foot sheets of Styrofoam at home depot. styrofoam has huge thermal efficency. think about this, a 1/16th inch thick styrofoam keeps boiling hot coffee from burning youre fingers. most coolers are made of styrofoam. styrofoam has better insulating value than the fibreglass pink owens corning insulation, or the blown in shredded newspaper, sor any sort of plastic. about the only thing that beats styrofoam would be asbestos (which i have some of but wont use it indoors due to heath reasons).
each sheet is about $15 bucks. and 1 sheet can do 2-3 windows. each sheet is also 4 inches thick and has a plastic thermal barrier on one side. you cut a square out of the sheet to fit snugly into the window frame, blocking heat and light. this has a HUGE energy savings benefit for my during the summer. it cut my a/c bill by about $75 each month. i blocked nearly all the windows in the house off.
the other neat thing about Styrofoam is that you install the white side facing out, so when you are outside the house looking in, it just looks like you are looking at a white set of curtains or blinds. and if you do have curtains or blinds, keep them shut so you don't see the Styrofoam inside. most people who visit my house don't even know i have Styrofoam in the windows, its that non invasive.
i think it cost me about $60 to Styrofoam all the windows in my house with 4 inch thick styrofoam. i used 1 inch thick styrofoam on my sliding glass door because if i used anything thicker, i wouldnt be able to slide the door open.
the best parts of using styrofoam is that its totally removable, there is NO bolts, screws, glue or tape used. you just cut a square out of the sheet and set it in place. when there is mild weather and you wish to open the windows, the removal of styrofoam is quite easy, just pull it out and set the sheets in the garage or attic. and the real big kicker is that styrofoam sheets make even the most inefficent windows super insulative. so it saves the need to upgrade to expensive double panes, etc.
its cheaper to run a lightbulb than it is to run the air conditioning.