There are a few sensor cleaning kits on the market that look pretty good, even those for the tin oxide coating Nikon uses in the filter part. 

Why do I mention this? The local service place will clean for free...but the kicker is they sell you the cleaning kit for $60!

About $50 will get me a good kit suitable for Nikon (though not recommended or approved by Nikon) with 12 swabs.

Do you clean your own?              TomDart.