When I worked as a photographer for Kodak in the UK, they supplied us all with several Sandisk Ultra II - which I am still using 8 years later for little jobs. Reliable then, reliable now (although they are now rather small capacity). Not the latest speeds, no 'glory' in using the biggest and best - just completely trustworthy. Who needs 'street cred' anyway?
However, one point which they absolutely ENFORCED was that we never ever did a whole job on just one card. This on the basis that if one card went bad, if it was lost/stolen (oh, yes, it happens) or some other misfortune like dropping it off a cliff (!) then we hadn't lost the whole job. This was really only an extension of the ancient practice of not processing a whole batch of films in one go. Belt and braces approach. Yes, it's a bit frustrating having to remember to change cards but it may just save the day. From that day on, I've always tended to use smaller cards but several of them (in fact nearly all my cards are only 8Gb). Personally, I would always advocate having several cards and using them in rotation rather than just one, all-encompassing big one. Even for holiday 'snaps' which are of little real consequence, this is the approach I adopt.
I've always found KINGSTON to be a thoroughly reliable make, along with Sandisk of course. There were, years ago, issues with Lexar specifically in Canon cameras but these seem to have been resolved a while back. Much depends on what is readily available in Australia - different markets have different levels of availability and what I can easily get in the UK may be like rocking horse effluent where you are. What is easily obtained in USA (population 314 million) may be no more than a rumour in Australia (23 million) and scarce in UK (56 million). Market size has a very strong effect on availability.
A lot of the slightly less well-known brands (relative to Sandisk and Lexar, no denigration implied) are made by Samsung. I used to know how to determine the make, but old age fades the memory just a tad. Transcend, Dane-Elec et al do have their following, quite probably with some justification, but I've always taken the view that with the investment we all have in primary equipment, why cut corners on something which may work perfectly but may also always leave you with a feeling of disquiet.
Remember too that card makers are in business to make money and it is in their interest to persuade you that you absolutely must have the biggest/fastest/most prestigious. But do you actually need that? I certainly don't these days - and actually never have needed it.
eBay? Not unless there is absolutely no alternative. If it is worth people's while to make fake rechargeable cells retailing at $2 each, it's certainly a good bet that there are (literally) boatloads of fake Sandisk selling for considerably more. An alternative perspective on this: quality control throws out a proportion of anything we make. What do you think happens to these 'seconds'? Landfill? Recycle? Sold on under other brands - that is definitely what happened with film?? Spend your money locally - at least then you have some comeback if there's a problem.