Has she even priced any of the materials?
So $800 for the water, a window & door from challenger or the like is $1500 from other threads on here.
Electrical panel & wire $200-300
$200 ++ for FRP, screws, adhesive, etc
$100 lights
$200 cheap floor tiles or Lino + adhesive
What about equipment?
That’s 3 grand right there, and that’s a conservative estimate.
Forgot the water heater… $200??