Pete,
It depends on what hull value you are insuring, but the costs you describe do not seem to be completely out of line with what others are paying, even with your high experience level. Here are a couple of threads to look at:
http://www.337skymaster.com/messages...=&threadid=759
http://www.337skymaster.com/messages...=&threadid=733
You could also do a search (Click on Search at the top of this page) using the keyword insurance to see many other threads on this subject.
Good luck in your quest...
Kevin