"unnecessary cost" is correct and usable in written English.
You can use it to refer to any cost or expense that is not necessary or beneficial. For example, "The company incurred an unnecessary cost due to the mismanagement of funds."
"We have so much unnecessary cost in our system," Mrs. Clinton said.
However, some are concerned that the installation of the smart meter displays is an unnecessary cost.
Even more problematic than the wage rate, some developers say, is the unnecessary cost of peculiar work rules and featherbedding.
Many tycoons still regard best international practice as an unnecessary cost, or even an instrument of western economic colonialism.
In the brief, the signers said the federal law "puts us, as employers, to unnecessary cost and administrative complexity".
"This dual regulation is likely to create unnecessary cost and confusion and produce no added value," they said.
"Huge and unnecessary cost" – so far unspecified but certain to be several billion – is therefore what the UK-minus-Scotland will face.
Latham, who's previously said the move would involve unnecessary cost and complexity, will be invited to apply for one of the new positions, NSW premier Mike Baird says.
He said it was now more important than ever to remove "red tape, regulation and unnecessary cost burdens" and he would fight to encourage new investment.
"We must eliminate every unnecessary cost in every aspect of our business," Chrysler's chairman, Robert L. Nardelli, told employees by e-mail on Friday.
Adding a built-in ability to replicate would add unnecessary cost and complexity -- unless one was trying to create a dangerous nanorobot as a weapon.
