These leads and plug type are very common, try an Op Shop or Salvation Army Shop, they normally have a drawer of them. Make sure you get the figure-of-8 type and not the lead with an oval shape of the same size, also very common.
It's not the least charm of a theory that it is refutable. The hundred-times-refuted theory of "free will" owes its persistence to this charm alone; some one is always appearing who feels himself strong enough to refute it - Friedrich Nietzsche