This offer just about halves the previous best (on a "per camera" basis): see here
This is a 4-pack of the basic wifi Tp-Link Tapo C100 (works out to $13.90 per camera).
And there is 11% discount if buy more than one pack (works out to $12.40 per camera).
[Edit: Good comment by @plasmapuff below… look at the "buying options" / "other sellers" sections on the Amazon page for alternate stores, and look at the PCLive seller (AU), as the Amazon UK ones will come with UK plugs (the Harris Technology option is OOS)]
This is a no frills camera (but with decent HD video), without cloud storage.
It comes with a simple app.
But the best bit… it is accessible via RSTP.
This means you can connect via VLC / NVRs, and there is an integration for Home Assistant.
These are coming via Amazon UK, so will not likely get here before Christmas.
I paid a couple of bucks extra to get it from Harris Techonology, but they only have a couple of packs left.
[Edit: Never mind… appears in CamelCamelCamel that these four packs have been at a good price for a while… but still - I think this deal is very good value]
[Edit: And here is some sample footage])
I just clicked on the link they provided in the message (https://www.amazon.com.au/returns), search by the order ID, and request for refund