Foodstuffs has announce it will decrease prices on everyday items by an average of 10 percent.
"It's really hard to see a reason why they're doing this for any reason other than increasing profits."
Fruit and vegetables have increased by 18 percent this year
Loose garlic prices are significantly higher at Countdown than at any other supermarkets.
Grocery staples such as lettuce, butter, cheese and mince are costing a lot more, shoppers say.
Members of the Budget Busters group commented on the grocery items they will and won't substitute for cheaper brands.
Eat Well For Less co-host Michael Van de Elzen and other budgeting experts share their tips.
"There is very limited competition in the NZ grocery market."
The commission launched new surveys on Thursday to give insight into whether competition in the grocery sector is working well.