If you are a regular seller of items on Neighbourly it's important to consider whether your activity is taxable as a business, or not. This helpful page from the IRD sets out some general principles relating to online trade.
If you're running a business, your income is taxable and your business expenses are deductible. But if it's a hobby, you don't pay tax on your income and your expenses are not deductible. The "business or hobby" issue can be complex, and if you're not sure you should seek advice from your tax advisor or the IRD.