Badger culls in Somerset and Gloucestershire have cost the equivalent of £5,200 for each badger killed, an animal charity says.
Official figures show the cost of £3,350 for every animal killed, but Care for the Wild said this did not include the cost of policing.
The charity had previously estimated it cost more than £4,000 per badger killed.
The government and farmers believe culling badgers will curb TB in cattle.
The pilot culls aimed to kill 70% of the badger population to test the feasibility of a nationwide cull.
The government said costs totalling £6.3m were due to rigorous monitoring of the humanity and effectiveness of the culls, with 1,879 badgers being killed by controlled shooting.
However, Care for the Wild said shooting the animals was not a good way to control TB and was a waste of money.
An independent panel of experts also concluded shooting was not effective or humane.
'Horrendous waste of money'
Care for the Wild's Dominic Dyer said culling "is inhumane, unscientific and is throwing money down the drain".
He said: "If every badger killed last year cost the taxpayer £3,000, that would be a horrendous waste of money on a policy that leading scientists say won't work.
"But the reality is that every badger killed actually cost £5,200 - and that is simply beyond belief."
He said bovine TB should be tackled by improving farming practices and better cattle movement controls.
In a statement Defra said the cost of the badger cull pilots "needs to be seen in the context of the devastating scale of the threat bovine TB poses to our farming industry and food security".
"Doing nothing is not an option," it said.
Both Avon and Somerset Police and Gloucestershire Police have refused to answer Freedom of Information requests from the BBC over the cost of policing the culls.