recently saw Birmane (Van Cleef & Arpels) advertised for £14.99 - this did sound cheap - I buy this for my sister who lives in Canada so any time I see a bargain I pick up a couple of bottles. BUT my local perfumier is selling 100ml for £12.50 and 50ml for £9.00. The so called Duty Free shops will also con you for £35.00 if they can and also sellers on e-bay will try their luck and often succeed but being a seller and a buyer we owe it to ourselves to buy and sell sensibly. For example, don't put a starting price on an item that you know to be way above shop prices - most of the buyers on e-bay are not silly - you will end up paying fees and not selling it. Don't use the argument that you didn't know how much it cost - do your homework and then you will save yourself the embarrassment.
So the moral to the story is not to get carried away by the bidding - sometimes things are lots cheaper in the shop, brand new, and mostly you know how long it has been around for.
But on the other hand there are many bargains to be had on e-bay - one of my favourites recently went for a song - I missed it by about 17p because I wasn't near my computer at the time.
So happy (honest selling and buying to all the e-bayers in the world.