Answers:
I found Mariage Freres Tea for you at several sites so you can price shop...
http://www.upstairsatpierrelafond.com/photos_11_the/mariage_page.html
http://www.sloanhall.com/bath/mariagefrerestea.html
http://www.la-societe-du-the.com/
Here's the original site but unless you can speak French don't bother...The English portion of the site is still underneath construction...
http://www.mariagefreres.com/
Other Answers:
I ran a explore for earl grey tea french cotton muslin teabags and came up near several results. I'm not listing the locations as to not SPAM Food-FAQ.com and to allow you to choose your own prices.