If you own and live in the property you can do Most of it your self.
Do you Want to hack into the electrical, plumbing and mechanical, and Understand Everything about them?
Thats why you pay someone with that knowledge, just choose carefully.
A mistake could burn or flood or collapse, injuring you and your family.
Thays where "the fun guys " come in, They are your best insurance policy.
Buildings , and the trades are done to a minimum standard, would you want anything Less for your Familys safety?
Good Luck and Be Safe
Your response tells me that you don't live in Edmond.
If you pull a permit you can't do any Electrical, Concrete, Plumbing, HVAC and other things yourself....olny licensed contractors can touch it (That means don't even install a ceiling fan - you need to pay a contractor $150 to do it)
"Fun Guys" are not an insurance policy..."Fun Guys" are the Ahole inspectors that nitpick crap to death for the hell of it.