We are in the process of replacing our ca. 1958 single-pane window sashes with wood double-pane sashes (the original windows are Anderson and they make replacement sashes that fit the original frame). This was much less expensive for us than replacing the entire window.
My DH is an architect and for aesthetic reasons he wouldn't even consider vinyl windows, so that is one of the reasons we're going this route.

We have about half of our 14 sashes done right now, and the others had been icing up earlier this week. I put plastic shrink wrap on the insides of the old ones and there hasn't been any condensation since. This is a good temporary measure.
Good luck.