I'll jump in and add my bit as I have been researching helmet standards a fair bit lately for our full carbon fibre helmets.
All Australian certified helmets are required to have the chrome AS1698 sticker issued by SAI Global (the governing body of standards), along with the sticker there is a serial number that is used to track the batch of the helmet. Simply having a red sticker saying it meets the standards is not enough. Although the red sticker may pass scrutinising does it by NO means make it comply with AS1698. Let's face it, a 30sec check over does not leave time to go over safety equipment in detail. Don't fool yourself that nobody in Australia is trying to make a buck from a product and putting on a fake sticker. The costs to get a helmet certified (Australia has one of the highest standards and toughest testing procedures in the world) is roughly around $25,000+ AUD. This is per style too, so you soon start to see why most of the 'good' helmets are $700+ as the production cost alone would eat into profit needed to reclaim the testing financial outlay.
I don't want to seem like I'm flogging my product, but I would NEVER buy a 'cheap' helmet. I'm a firm believer that you do it once and you do it right. I'm not going to debate the likelihood of you having an accident, but I will say that if you were in an accident and lying in hospital you might reconsider the amount you spent on your helmet because brain damage is forever. Besides we all know motor sport is not cheap. I'll finish with an old saying, only put a $50 helmet on a $50 head.