I bought a used Pentax 18-55mm lens to try on the KP.  The above are some of my first test images made with it.  So far, I like it in that it is good enough for this type of photography.  It is the best $130 lens I ever bought and it focuses close enough for flowers, etc.

I also used it at 55mm focal length for a distant image and then cropped in tight to see how it resolved.  You can see for yourself below.