While not the all-time lowest price ever, the prices for Thief (2016) and The Turing Test are pretty good.
So, this is a good chance to get the games cheap provided you want to play those games anytime soon (if you only want to play them in two years, then chances are that the games will be even cheaper or bundled at the $1 tier in some bundle by then).
The Turing Test: https://store.steampowered.com/app/499520/The_Turing_Test/
The Turing Test Collectors Edition is also at a good price: $6.86 AUD:
https://store.steampowered.com/bundle/1002/The_Turing_Test_C…
Thief showing up at A$44.95 for me and Turing Test as A$28.95. Think it's expired.