I'm calling BS on the "high quality wood isn't available today" I can think of at least 5 species that are as good or even better than old growth heart pine, douglas fir, white and yellow/long leaf pine not even looking at synthetics. World trade pretty much squashed the "they don't grow them like the used to" talk. Old windows can be referbished/reconstructed to a pretty high energy efficiency. The jambs get insulated, weather seals added and sashes replaced with insulated glazing. It's very expensive at roughly $1000 for an average sized older home type window. Removable storm windows are also a good option to keep the look of the old windows. Basically they are single pane glass, center rail in a wood frame with weather seals.