I've not heard of one. You could try the find open source support link from the nagios site findopensourcesupport.com/se ... 0&software]=1&software_lock=1
Or mail Ethan directly - he might know of something.
Really the hardest thing with Nagios is getting the first few hosts going. You start off with loads of empty config files not knowing what on earth to do. Once you get past the first couple of days, things start falling into place and you'll soon get the hang of it. If you get stuck at any point then just post the problem here I think you'll have a much better understanding working through the problems than learning from a course.