I'm no expert on this, but I have read a couple of horror stories about silk thread deteriorating over a period of about 7 years. If you are interested in cotton thread instead, here is a link to bobbin collections from Superior:
http://debbiesdabbles.blogspot.com/2...-for-hand.html
http://www.pieceocake.com/Notions/thread.html
The only silk collections I could find are spools.