As a general contractor, assuming you are doing things(paint, flooring, maybe light fixtures and blinds) to the entire 3000 sq ft, your budget that remains purely for tech is going to be approximately zero. Its doubtful that budget would even allow for much of a kitchen/bath update depending on what part of the country you are in.
Not if they do most of it themselves. I've redone the floors, moldings, painted, replaces lights and door hardware for less than 4000 in my 1000 sq ft condo. Once you start talking major appliances it gets much harder to save money, but cutting out labor saves a ton of money and you'll learn some useful skills.
When you are working hard, get up and retch every so often.