Odd isn't it? It's a very sought after book yet the Amazon UK warehouse deal I found, gave me a totally unused copy still boxed and cellophane wrapped internally for £46 ($73)...and I think that included free delivery! That Amazon page is now showing the cheapest used copy at £167 ($256) and the cheapest new for £650 ($997). Father Christmas obviously thought I'd been a very good boy...
The problem is establishing which edition you are buying. One French magic site was selling a 'first' through Amazon which transpired to be the revised edition once I'd sent them a guide to the differences. They seemed genuinely shocked and apologetic and removed it from sale...