Technology is changing the huge global market for record collectors. As music dealers like those immortalised in the book High Fidelity disappear, will vinyl and CD rarities survive the download revolution? Second-hand record shops are becoming almost as rare a sighting in the UK as a first edition Beatles EP. The days of shuffling into grubby backstreet stores in search of that obscure Pink Fairies seven-inch are on their way out as dealers succumb to the march of online auction sites and MP3s. CURRENT RARITIES U2's Trabant car: £6,000 Queen 12" single: £10,000 Withdrawn Nirvana CD: £500 Led Zeppelin seven-inch:...