According to your post, he never said he would "buy" your cable, he only said he would "but" it. And, he said it twice.
Reminds me of Woody Allen in "Take The Money And Run" where he tries to hold up the bank...
Hey, for all we know, he may just have butted it.
Seriously though, when you sell gear, you are going to see all kinds. ALL KINDS!
I agree that feedback is only applicable to a deal which has more or less gone through. In this case, I don't believe it is within your rights to leave feedback. Instead, doing what you have done, starting a thread, is more appropriate.
My advice is to vent here and move on. Move on from this pseudo buyer. While it has been suggested that he may not be getting your e-mails, the means in which it happened twice makes him look like a clown. I believe if the fault did not lie in his lap, and he did not receive your reply, he would have sent additional correspondence asking you why you didn't respond or what was going on with the deal. Instead, he shows up again just like the first time, as if nothing happened.
Keep repeating the saying, "Fool me once, shame on you. Fool me twice, shame on me."
