Wow, that's an old one. I just renovated (almost from the frame up) a 1922 farm house and I'm unlikely to ever do it again. As a simple example; That electrical work... only a large outfit with an extensive insurance policy (and thus higher prices) was willing to touch anything electrical in the house because of liability.
Put a simple floor in and now you're removing old flooring and layers of it, who knows what it's made of, and now you may as well consider leveling any low spots and driving a thousand screws to get all the creaks out before you put the new one in. It's all 2-3x the work honestly.
Need to swap out some door hardware? You may be swapping out an entire door instead and chances are it's odd sized. Expensive and time consuming.
And so it goes with just about everything. HD and Lowes don't carry a lot of odd items you may need either. Insulation, if needed, is a royal pain depending on floor layout.
Don't intend to sound negative, just reflecting on a long and painful process that never failed to amaze me!
Good luck!