Been a while since we had one of these Ryobi twin battery/charger kit deals. This is showing as 'limited time' on the Ryobi website so it's a promo. When it sells out, its gone.
Might be wrong, but pretty sure the last deal like this was August last year. That was the same charger but 2 x 5.0AH batteries for $239. https://www.ozbargain.com.au/node/863105
Charger RRP is $169, 4.0AH twin pack RRP is $199, and a single 4.0AH is $149 RRP.
Fair bit of stock around and now available in W.A. https://bunnings.youinstock.com.au/search/0873101
This deal probably best suits those who want a better charger than the single one that comes with most kits. Or if you don't want the charger, you could just sell it and end up with some pretty cheap batteries.
Does not appear to be available in WA