if your rich you can use the Rio bite tippet 20lb at $1 per foot
this stuff is a knotable wire that is .018 thick
I went to Michaels craft store and found some wire that is very similar in its makeup, not quite as soft as the Rio stuff but i rather it be a bit stiffer. I bought the diameter that was closest to the Rio stuff. I think the craft wire is actually stronger honestly.
the wire MUST have the clear plastic coating or coloured if you so desire but make sure its coated wire. brand name i have is Beadalon if i remember right (cant go look at the moment cause wife is asleep)
I would say .015 - .018 is going to be plenty strong enough especially because its doubled over.
TIP - put the hook onto the wire before tying it on otherwise the hook will ride sideways