Where else can we get a genuine Dyson V6 replacement battery please?

Hi there we have a Dyson V6 Total Clean vacuum that is on the blink, the battery fully charged is only lasting 3 minutes and as we have a constantly moulting Basset Hound we need our hoover working.
we contacted Dyson today who quoted us £65 for a new battery with 1yr warranty but I just wondered if there are any only stores selling authentic Dyson batteries any cheaper please? With Christmas round the corner times are very tight.
thanks a lot folks