“Can also have decorative rocks shown in picture if you want them.”
So the decorative rocks are not part of the pond? What then is this Koi pond comprised of, exactly? A hole in the ground? Perhaps some algae-clouded water?
Other things this person will probably allow you to take off their hands if you ask nicely: windows (not the frame or the glass—just the empty square of space), the task of pushing a boulder up a hill repeatedly for all eternity, the sound of one hand clapping.