Our temp disagreements are over actual comfort rather than cost - he wants it cooler than I can manage well, winter and summer, and can't sleep well in temps I'm comfortable at. Our solution is an electric blanket for me in winter and extra covers in summer. Cost isn't much affected, really, because of the way we built this house, earth sheltered with extreme thermal mass.
Marital peace is priceless; if he's miserable from lack of sleep, I can't possibly be happy.
+1 to those who have mentioned menopause as a factor to be taken into consideration; we got much closer to agreement on temperatures during that time, as I wanted it cooler, too. It was a silver lining to an uncomfortable time, but it seems to have mostly passed.