Looks like it's $3 per episode, or $20 for the season.
Link
Charles, thanks for mentioning that it's on Amazon Video! I had lost all hope of watching it legally this season and I hadn't seen this option mentioned anywhere else on this sub. I'll gladly pay $20 for a season - that's only a dollar an episode!
Whole of Season 3 for $30
In the US you can subscribe to the season via amazon for $30 and watch that way (with no commercials!).
https://www.amazon.com/dp/B07D1MWXXR
It streams via Philo: https://try.philo.com/
And also streaming cable systems like Direct TV Now also have discovery in their basic package.