i did a quick ebay search and found 400# monofilament, and 100# monofilament. the 400# doesn't show the actual line, so i don't know how bulky it is.
http://cgi.ebay.com/Ande-400-Lb-Test-Cle...1QQcmdZViewItemthe 100# line looks fairly normal, and for fishing, sewing, lashing, etc, i inagine 100# would be more than sufficient, unless you're fishing for sharks.
http://cgi.ebay.com/Anbe-Monofilament-10...1QQcmdZViewItem(i am in no way affiliated with either of these sellers; i'm just listing examples.)