I agree with Herman: forget about it; life's too short.
For the sake of analysis, my guess is that this seller received an offer before yours. He agreed to sell it, and the buyer paid via paypal, overnight delivery of cashiers check or money order, etc. Until he could confirm payment, he decided to string you along with a delaying tactic. In other words, if the first buyer didn't pay up, he would still have you as an interested buyer. If he had told you the cable was already sold, you might buy one from somebody else (e.g., order it from a dealer) before he could confirm payment from the first buyer. While this is not a nice thing to do, he technically did not lie to you. It appears the first buyer came through with the payment, so the seller was willing to come clean and say the cable was already sold. Find another seller!
For the sake of analysis, my guess is that this seller received an offer before yours. He agreed to sell it, and the buyer paid via paypal, overnight delivery of cashiers check or money order, etc. Until he could confirm payment, he decided to string you along with a delaying tactic. In other words, if the first buyer didn't pay up, he would still have you as an interested buyer. If he had told you the cable was already sold, you might buy one from somebody else (e.g., order it from a dealer) before he could confirm payment from the first buyer. While this is not a nice thing to do, he technically did not lie to you. It appears the first buyer came through with the payment, so the seller was willing to come clean and say the cable was already sold. Find another seller!