The values can very greatly based on requirements. Things to consider as someone who has rehabbed homes are plumbing costs if you plan on adding a bathroom upstairs.....electrical costs if your current sub-panel is older and not sufficient size or style (screw fuses, etc) to support the addition. Structural issues downstairs to support the addition could increase costs. To reduce costs in materials, look at the condition of rafters and ridge beams for re-use of some materials.
I would do you a tremendous disservice by rattling off a price range with so many variables, lack of knowledge of your requirements upstairs (2 bedrooms and a game room, or a bathroom, or you trying to put in a rentable apartment with a kitchen, etc) and lack of current structural, mechanical and electrical component knowledge. I would shop around, get recommendations and definitely get at least 2 or 3 estimates before committing to a contractor. Good luck.