I've previously bought from this mob and believe they are selling genuine Duracell batteries in trade packaging aimed at tradies, etc. who need commercial quantities of batteries. Last time I got 20 for about $12 delivered but with inflation they're slightly more expensive. There's also a last pack of 40 batteries for $24.97 here https://www.ebay.com.au/itm/326182833095?mkcid=16&mkevt=1&mk…
I use these in my ZigBee devices and also use them to replace the larger but much more expensive CR2450 by using a 3D printed adaptor.
Edit: looks like smaller quantities sold out but if you need 100…
gone