The Conservatives have claimed that the cost of a British general election to taxpayers will triple to almost £300 million under AV.That's odd, because according to Hansard, Mark Harper, Parliamentary Secretary (Political and Constitutional Reform), Cabinet Office on 4th April 2011 said:-
Based on the information set out in the Parliamentary Elections (Returning Officers' Charges) Order 2010, the estimated cost of the conduct of the UK parliamentary election in Great Britain which was held under the first past the post system on 6 May 2010 is £82.1 million. This figure takes into account the reduced costs of holding the UK parliamentary election on the same day as local government elections. The estimated cost of the 2010 UK parliamentary election in Northern Ireland was £2.5 million. The overall figures will be finalised once all claims from acting returning officers in Great Britain and the chief electoral officer for Northern Ireland (who are statutorily responsible for running the poll) have been received and finalised. The estimated cost of holding a stand-alone UK parliamentary election across the whole of the UK under the first past the post system is £92.1 million.
The features of a general election using the alternative vote system would broadly be the same as under the existing system: for example, in terms of the provision of ballot papers and polling stations. However, it is not possible to quantify with certainty what the extra cost of counting votes under the alternative vote system would be: this will be dependent to a significant extent on the preferences expressed by voters.
If you're going to lie about the costs of AV, it's probably best to check that one of your own Ministers hasn't already said something that blows your claim out of the water.