These are very good, all-time lowest prices for these games that are all rated positively/very positively on Steam. All prices are in AUD.
Earthworms: $3.40: https://store.steampowered.com/app/320330/Earthworms/
Age of Empires II HD: African Kingdoms: $3.62: https://store.steampowered.com/app/355950/Age_of_Empires_II_…
Her Majestys Spiffing: $4.24: https://store.steampowered.com/app/488770/Her_Majestys_SPIFF…
The Yawhg: $4.24: https://store.steampowered.com/app/269030/The_Yawhg/
Peace, Death: $1.99: https://store.steampowered.com/app/588690/Peace_Death/
Rise of Insanity: $5.07: https://store.steampowered.com/app/629220/Rise_of_Insanity/
Spark the Electric Jester: $3.99: https://store.steampowered.com/app/601810/Spark_the_Electric…
Enjoy!