Use your judgement – if its too good to be true, it probably is.
NEVER pay via credit card to avoid credit card fraud.
Pay with PayPal where possible to benefit from PayPal buyer protection.
It is YOUR responsibility to avoid importing illegal and dangerous products. Stay away from imitation weapons, lasers, fireworks, telecom/radio equipment that operates in illegal frequencies. Customs will pick it up and you will be fined $$$. Don't trust the sellers specs on lasers – if Customs tests it and it is mislabelled, YOU will be held responsible.
Consider your safety: cheap make-up products from china may contain very dangerous/toxic chemicals!!
You will get what you paid for – if its cheap, don't expect high quality or precise manufacturing, build quality or reliability.
It is common for popular products to be 'cloned' by a different manufacturer at a lower price, often at a cost of lower quality. It is even common for clone products to be cloned! (e.g. SJ4000 action camera) Often these stores can be a good way to buy high-quality products designed for the China market, but cloning is rampant so be careful.
Do not be fooled by the photos, do your own research.
Some are well-known stores others are not. Do your own research on google and search the choicecheapies forums.
These are international stores. Don't expect them to honour price errors or New Zealand consumer laws.
If a product seems substantially cheaper than elsewhere ask – how yourself: could they have cut corners manufacturing this product? Will it perform to the same standard and am I happy to accept this if not?