Try these links
http://www.amazon.com/Dritz-920-Cone-Thread-Adapters/dp/B0018N3Z6E

http://www.ebay.com/sch/sis.html?
_nkw=Pkg+2+cone+thread+adapters+sewing+and+sergers

http://www.thecolorfulworldofsewing.com/Serger-Large-Cone-Thread-Adapters.html

http://www.joann.com/cone-thread-holder/13059563.html