Managing director, Tony Baas, said about 30 buses from the company's South Island operations were on the market.
Selling buses "from time to time" was a standard practice for the company as transport work demands fluctuated, given operational requirements, he said.
"Selling buses is part of what we do." Several factors influenced company decisions to sell buses, such as demand for transport services, and the age of individual vehicles, he said.
Passenger Transport, which bought Citibus from the Dunedin City Council earlier this year, routinely sold up to two buses a month, he said.
Buyers often bought the vehicles for conversion to private motorhomes. Smaller bus companies sometimes bought vehicles to add to their fleets.
Passenger Transport operates a fleet of between 200 and 300 buses from its four South Island depots, in Invercargill, Dunedin, Queenstown, and Christchurch, making it one of New Zealand's top 10 bus companies in size, Mr Baas said.
"Our overall fleet size remains pretty stable."
The company had bought about 10 buses this year, he said.
A large proportion of the buses for sale were from Invercargill, he said.
Two had been advertised outside the Citibus Princes St depot, and up to 10 buses were being sold in Kaikorai Valley, Mr Baas said.
On average, the buses retailed for between $8000 and $10,000, although newer models could cost up to $20,000.
A few buses were also sold to scrap metal merchants.
