Got him - David Knisely
See
http://www.cloudynights.com/item.php?item_id=1520
This is an article about types of filters. He has other threads/reviews on specific makes and often contributes to questions about specific filters in the Equipment forum.
Eg:
http://www.cloudynights.com/byauthor.php?author_id=2
See also:-
http://www.prairieastronomyclub.org/filters.htm
At the moment, you will likely buy cheaper from a US retailer and postage won't be much for filters. But they cannot sell some makes outside of the USA.