The list of items available for prisoners to buy spans 167 as of November 2022.
Since 2019, many have risen in price.
A sheet of 10 stamps has climbed from $13 to $15, while a five-pack of Mi Goring noodles has risen a dollar, from $3.25 to $4.25.
Beef and chicken instant noodles had risen from $2.40 to $3, while most drinks had become more expensive for inmates, with powdered drink mix increasing by 10c to $1.75 and diabetic cordial increasing by 15c to $4.40.
The price of hot chocolate leapt from $3.55 to $5.25 and similar increases were seen in the price of whole milk powder, which increased from $4.80 to $5.95, and skim milk powder, which went up 90c to $5.50.
About 30 items declined in price including cassava chips, which fell from $3 to $2.25, and salted peanuts which fell 10c to $4.65.
Cashew nuts dropped from $5.20 to $4.70 while dried apricots fell from $6.40 to $5.10.
Portion sizes were not provided for all items across the two time periods.
In a statement, Department of Corrections deputy national commissioner Brigid Kean said prisoners were provided with essential items and meals.
Prisoners who met the criteria could join the prisoner incentive allowance framework, through which they could receive an allowance.
"This is not a salary or wage, but rather an incentive to encourage prisoners to take part in activities that we know can help with their rehabilitation and reintegration," Ms Kean said.
The framework was introduced in 2002 and its rates had not changed since 2004, although it had been reviewed several times since.
She noted television rental fees for prisoners were waived last year.
"The purchasing power of prisoners is not necessarily impacted by inflation in the wider economy," Ms Kean said.
Another Official Information Act request showed the framework allowed prisoners to earn up to 60c per hour.
A Corrections spokesman said most price increases were less than 50c.
Inmates at Otago Corrections Facility were able to submit a request form each Friday, either on paper or through a kiosk.
The forms were processed and the items delivered from one of four distribution centres the next week.
