My original entry was bidding to discourage the seller from pulling the coin and selling it to someone making an offer. I have noticed that this happens a lot. I won't make a habit of identifying rarer coins on ebay, but this was a one off as an example of the type of coins that get pulled from auctions and possible ways of stopping this happening. I don't generally bid on coins that I have an example of in my collection, but do go for the "Buy it now" when they are a bargain !
As some of you have mentioned that you have managed to buy rarities that have been little recognised, I will not bid on any auction coins that I don't require for my collection, but as I have said before, I advise you to make a bid within the first days of an auction to show your interest.