Rebel, I just got some "Tufnol" from Toni Clarke in Germany. It is available in a variety of thicknesses, (FYI 3mm is approx 1/8") I ordered 5 sheets on a Monday and had it delivered on Friday! And it was about $10 from Europe. See here:
http://www.toni-clark.com/ftp/cat_11..._1_2010_en.pdf Page 117
Martin