Waitaki mayor Alex Familton has questioned the $5 million figure quoted for the upgrade of the Oamaru courthouse.
The town's courthouse has been closed since late last year pending an investigation into its earthquake resilience.
Mr Familton says he's stunned by the estimate given by Minister for Courts Chester Burrows.
He says local engineers have suggested the upgrade could be done for just a 10th of that cost.
The courthouses in Oamaru and Balclutha are two of nine across New Zealand to be reclassified as hearing-only establishments.