40mm for the K01

When I purchased my K01, I was planning on getting the body since I have the 50mm, 28-55, 50-200 and tamrom Pentax 18-200/

The sales rep said for an extra 95, it was a steal and I could see it for 200.

I have to admit I like the size and the 4-5 pics it took inside with low light. My biggest fear is lossing those small plastic caps. Any idea where to get a fell? Considering keeping it.