You can buy individual sprockets.
http://www.petracycles.co.uk/cassettes-cassette-spares-c-253_274_275.html?osCsid=2ebc3b18312952f7275168d0ce1ee143
Are you sure the gearing is adjusted well? If so, then you should probably replace the whole cassette if it's that worn.
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You can buy individual sprockets.
http://www.petracycles.co.uk/cassettes-cassette-spares-c-253_274_275.html?osCsid=2ebc3b18312952f7275168d0ce1ee143
Are you sure the gearing is adjusted well? If so, then you should probably replace the whole cassette if it's that worn.