"And if food prices continue to increase the way they are then suddenly I'm more vulnerable than I've ever been."
Power price hikes mean that this will be the first winter her family will not be in credit with their power provider. In the past Sarah has been able to build up a credit balance over the summer and that's seen them through winter, warmed by a single heater in the flat.
She's been relying on the DPB for seven years which is most of the time she'd had been living in Wanganui. She came out from the UK with her then husband 16 years ago but after they separated she was left raising three children.
At the end of every week, her bank account is empty.
"I haven't got any savings. I've got nothing. Perhaps living on a benefit for a short time is manageable but when you have to go years with it it's a different story," she said.
It's not that she's afraid of work. She does part-time cleaning and gardening jobs wherever she can and that extra income meant she could run a car. But now that luxury has gone too.
"When I've been able to get it I've done seasonal work but just when winter arrives that job goes and you've got no income again."
Sarah's even taken to buying and selling on Trade Me, selling off what her children no longer need to generate money to buy them something they do need. She's experienced in textile design and uses that creative talents to make Christmas presents for her children.
In spite of her hardships, she started studying for a diploma in business administration at Whanganui UCOL, planning to find office work when her youngest started school. But then staff cuts at UCOL meant the timetable changed.
"I couldn't get morning daycare for my youngest so I can't continue my course," she said.
Now she has her heart set on a nursing degree course at UCOL, a three year journey that starts next February. She knows it will be tough but knows the long-term rewards will make it worthwhile.
"Maybe when I graduate I can save to have a car and take the kids on holiday. The last time my middle child had a holiday was when she was four. That's eight years ago.
"You don't look too far into the future. To get the nursing degree would be fantastic and to earn that sort of money would be a dream come true," she said.
Sarah frets about the widening gap between a basic living wage and the cost of living, and worries about what the future holds for her children.
"What we need in Wanganui is jobs. It's that simple. The idea of a living wage of $18 an hour is hugely appealing. The difference between a benefit and the basic wage is marginal and I doubt if anyone on that wage is any better off than I am at the end of a week."
Sarah said she feels trapped relying on a benefit "and it's hard to see how you can make things better".
"I get really cross when people say it's a lifestyle choice or you're lazy. It's just not true at all. If someone gave me a job, 9am to 4.30pm five days a week, I'd take it. I wouldn't care what it was. If I can improve the quality of life we've got and earn enough money to pay all my bills and have some money to save that's all I'd want.
"I don't even have money to put away for a retirement. I'm in my 40s and I don't have any spare to put away. I wanted to start KiwiSaver for the kids but I can't afford any money to put into that either."
She has friends who live far more comfortably than she does "but they just don't understand".
"They'll ask me out for coffee but I can't even afford a cup of coffee."
She can't remember the last time she went out socially. She used to take the two youngest to the movies during the school holidays for a treat. That hasn't happened for the last two school holidays at least.
"They don't get pocket money. I'm trying to teach them how to save but if they don't have money that's impossible. They're all little hidden costs you don't think about."
Doctors' prescriptions sometimes sit on the shelf because she can't afford to pay.
Sarah only shops for specials at the supermarkets and looks for bargains with fruit and vegetables. And the family gets by on the generosity of others who will drop in a bag of vegetables here, some fish there. It all counts.
She's become resourceful because she's had to: "I've learned to fix things. If I need to find out how I'll Google it." She doesn't carry contents insurance because, again, she can't afford it.
"When you're on the DPB it's the children who miss out. Sure, it's tough on an adult because you're financially tied. You can't do hobbies, you can't go out and buy things when they break down. You just don't have the money to replace things."
Her central city flat is an obvious choice because it keeps everything within walking distance.
But simple things are a burden. School uniforms and stationery are a huge expense. Then there's the explaining to be done when it comes to a request for a cellphone or iPad because school mates all have them.
What has proved a saviour is Sarah's cooking skills.
"You have to find ways to be creative. We live on beef mince and frozen chicken because you can do so much using them as a base. But if you haven't got those skills I don't know how anyone can survive," Sarah said.
She grows herbs and a bit of silverbeet but the section is tiny and not big enough to create a decent vegetable garden.
How do the children handle it?
"The oldest one's really good and she understands. The 12-year-old is embarrassed by what we don't have. She wants to do things but I have tell her sorry, but we haven't got the money.
"That upsets me because she's got to find something that she's interested in or good at, and it's my job as a parent to try and make that happen. But it's just the sheer cost of everything," Sarah said.
The free swims offered at Wanganui East pool this summer were a bonus and the 12-year-old was there nearly every day with her friends. But when the freebies stopped so too the swimming.
But despite these hardships, Sarah remains upbeat.
"I can see light at the end of the tunnel. I'm absolutely determined I'm going to get through that nursing degree because at the end of it I'll be earning money. Imagine being able to buy things without having to worry how I'm going to juggle my budget to make it happen.
"I'm lucky there is a benefit. There are a lot of countries that have nothing like this and that puts things in perspective. We don't have any spare money but we have a roof over our heads and full tummies. That's how you've got to look at it."