As a consumer, I found Amazon here (AU) ridiculously overpriced. The shipping is fast, so if they have the thing I want and I need it urgently sometimes it's worth it, but generally you'll get it cheaper at the local online stores like Big W/Target/Kmart/JB/GoodGuys/etc, or the small independent stores who run their own websites. Discoverability sucks, and sometimes you spend a couple hours (or even a few nights) searching around all the little local stores buried 5-10 pages down the search results to find what you need, but it's generally worth the effort for the better prices and local support.
Ebay is even worse than Amazon now though. I was an avid Ebay user from when they first came here until not long ago, but in the last year or 2 I find it's just chock full of scams, fake products, lies about shipping (advertised as local stock with 2-5 day shipping, arrives 4 weeks later with postage marks from China), etc etc. I flat out just don't trust anything on Ebay anymore unless it's an actual local individual selling something used and I'm picking it up.