You could use a ''Wild Country Cordelette'' and cut it into two (they come as a long sewn sling/loop for climbing, just cut it into two equal lengths for each end of the hammock) They are:--
400cm long (13 foot)
Lightweight at only 135 grams (thats 67 grams for each end of hammock)
Very strong at 22 KN breaking strain (thats 4,945 lb)
Dyneema so no stretch (no stretch preferable for hammocks)
They are about £23 (which means £11.50 for each end of hammock).
One Wild Country Dyneema Cordellete cut in two and a lightweight carabiner each end of hammock is all you need.
If thats too dear you can buy nylon climbing tape, or tubular polyester webbing is quite cheap though heavy, if weight is not a concern ''LYON'' make long webbing slings 480cm which are a bit cheaper.
Wild Country Dyneema Cordelette:-
http://www.needlesports.com/Catalog...sy-Chains/Cordelette-WCO-CRDLTTE#.VWR2zFKE11U