Those are the ones Nikon makes for that, right? The problem is that the lens filter thread is a special size, not your standard size, so that it makes it difficult to get filters unless you go to a third-party vendor to get a special adapter to put on there first and then you can use any standard size filters you need. I am drawing a blank here -- it's a place in Canada which sells custom-made filter adapters for the 8800 and sells them at a very reasonable price. Armed with one of these you can then purchase filters in whatever size you want.... Hm.... I think it's Nextphoto, but I'm not sure. Run a Google and it should show up....
OK, I just ran the search and it's nextphoto.net. Enjoy!