Kit lense replacement
This is just my personal experience. I bought K-x with 18-55mm and 55-300mm kit lens, pretty much covered everything. One month after I tried both lenses, I am very satisfied with them. They are very good, sharp, good bokeh, etc. Now, I wanted to get hands on some macro photography, neither lens can give me that capability, and I can't afford for a dedicated macro lens. So I searched for some cheap alternatives. I ended up with two little 50mm lenses (f2 and f1.7), pretty cheap on ebay. I tried reversed and stacking them together, pretty cool! I keep the smc M 50mm f1.7 lens on my k-x for night shots (especially for Christmas), very sharp, nice color.