I had asked Best Buy about the camera cleaning and they couldn't give me an exact price. They said that they send it out to be serviced and the that camera is completely taken apart, cleaned and put back together. Sounds a bit excessive to me. I've had a Coolpix 5700 for about 7 or 8 years now and never had it pulled apart and cleaned. Then again, it is all one unit and Nikon took care of me on some issues 2 years ago - even when the camera was out of warrenty. That is why the got my business again.
My biggest concern is the children around the camera. If the camera needs to be cleaned regularly, then the cost would be worth it for the "warrenty". Even at $30 a cleaning, it would pay for itself and give me peace of mind. However, like I said about the Coolpix - never had an issue that Nikon didn't own up to. It is still working fine after all these years.