IMHO, that type of behaviour would be likely to lead to their being no chance whatsoever of ever buying the stuff, if it was a legitimate offer originally. No disrespect intended, but what you describe above comes across as being borderline stalker territory. It needs to be kept in perspective that these are merely vices and anvils. The world isn't going to end for lack of them, and there's definitely no need to hound someone excessively for them, especially when they've already expressed disinterest in a deal.
A simple message to the chap from twertsy asking him to keep twertsy in mind if he does ever decide to sell is all that's needed. He'll probably never hear from the "seller" again, but at least he knows he won't come across as, (again, this is meant with no disrespect, but I honestly can't think of any other way to phrase it), creepy, hence may stand a chance of being considered in future, if the occasion ever arises.