There are a few of those sellers on eBay and Gumtree. Ask them a question and you are more than likely to cop abuse as an answer. Some of them make it clear they have no time at all for buyers but at the same time they want top dollar for their rusty old bits and pieces. One notorious seller uses ebay for his advertising but will not accept payment through ebay checkout. He demands that the sale go ahead privately. I always get the feeling some of these fellas must be sitting on mountains of scrap metal behind a ten foot high fence patrolled by a mangy old cattle dog with three legs and one eye, and they spend their days loosening up nuts and bolts to free up a few very rusted or corroded parts to flog off to the punters on ebay. Good on them I suppose. I guess it keeps them out of the pub and a few are making a good living out of this, while also constantly crying poor and complaining that ebay is robbing them blind. I always find it interesting that this "type" of seller often treats buyers as if they should be begging and grovelling at their feet because only they possess these sought after parts of immense rarity and value. So we must respect them and not quibble about the price, just accept whatever they are willing to offer us for whatever is in our wallets, at the same time making it clear that we are getting the bargain of a lifetime while they are the ones who are getting ripped off. In some ways it is true that in some cases they are sitting on gold mines of rare parts, in other ways they are simply cannibalizing rusty, worn parts from a scrap heap and trading it as "gold", while being generally obnoxious towards their buyers.
