I tend to group my online retailers into two categories:
1. Great providers - characterised by good customer service, frictionless purchasing experience and fast delivery times/click and collect, Australian stocked goods, and competitive prices. E.g. Amazon, JBHifi, Good Guys, Umart, Computer Alliance, bulknutrients
2. Lower quality providers - customer service is erratic and may be non-existent. Shipping times are erratic, may be shipped tomorrow, maybe in a week. Delivery times are highly variable, may show up in 2 days, may show up in 3 months. But the prices are so low that they justify this inconvenience. Some of these guys run local operations, some are overseas. E.g. Ebay international vendors, Gearbite, Alibaba, Banggood.

I've bought from Kogan a few times, and have had some ok experiences, and then a few incredibly frustrating ones, where I felt gouged and messed around. I think the main issue I have with Kogan is that their size and presence should put them solidly into group 1. But my experiences with them place them solidly in group 2.

If I'm looking for a product, there are many places I'd go to before hitting Kogan.