The new routemaster-style buses will cost £354,500 each.
But Transport for London claims that the final contract, signed with manufacturer Wrightbus, has saved millions of pounds for the taxpayer.
They say the contract "includes a competitive, fixed price deal for the vehicles - removing the risk and uncertainty of higher production and material costs, and inflation over the next four years".
TfL says the price is "broadly comparable with a standard hybrid double deck bus", with the difference "accounted for by the much higher specification of the new bus compared to a standard hybrid bus".
They also claim that the new bus is "the greenest diesel electric hybrid bus in the world".
More top news
A 15-year-old school boy has been stabbed 'five or six times' on his first day back at school in north London after the summer holidays.
Today's showers should clear overnight - and tomorrow will be more settled, but temperatures still feeling cool.
The pair have been poring over old maps and records in their bid to convince the council the warehouse should not be converted into flats.