I don't think anything I've bought was out and out stupid, but I did buy 6 packs of trading cards from the States for $7 and ended up paying £10 for postage and £7 for a US bank draft

Before Paypal, that was.
And I bought a guitar that was a heap, and missed all the signs in the auction because I'd convinced myself it was a good buy- but I saved that one, and nowI love the guitar, so it kind of worked out.
Just waiting to see if the T in the Park tickets I bought on Ebay ever turn up though.