Sensor cleaning, D7k.

I have a D7k that needs sensor cleaning. It's been camping, it's been to Scotland, it's seen many lens changes made in a not advisable way, in not advisable situations.

The sensor is pretty dirty. I'm not really comfortable cleaning the sensor myself. I suppose if the cost to have it done is outrageous, I can figure it out myself, but I'm hoping the community has some suggestions for where to get my sensor cleaned, and about how much it will cost.

Barring that, any tips/suggestions on how to do it ones self?