We were doing our weekly shop earlier and I noticed Coles had the regular size bag (165g) on sale for $3.85 - works out to be $23.33/kg. Right next to it though I only noticed today that the party size (290g) is actually only $5 (since Nov 2022) - or $17.20/kg. This means the 165g when not on sale is actually more expensive than the 290g bag.
So even when 165g are on sale, you still get more spuds for your bucks by going party size.
Seems to be the same for all varieties.
Enjoy your party sized gains!
I think they used to be RRP $7, and $3.5 on sale