This has been on sale before, but it's back. Each of the Jackbox games are discounted to varying degrees:
1: https://www.humblebundle.com/store/the-jackbox-party-pack $8.74 USD (~11.54 AUD) 65% off
2: https://www.humblebundle.com/store/the-jackbox-party-pack-2 $11.24 USD (~14.84AUD) 55% off
3: https://www.humblebundle.com/store/the-jackbox-party-pack-3 $14.99 USD (~19.79 AUD) 40% off
Steam keys provided for redemption
I think your prices are wrong. Are you getting those prices coz you are subscribed to the Humble Bundle Monthly thing so it gives you an extra 10% off? As that changes all the prices you have just listed.