As a plugged-in member I gave them $9/mo ($108/yr) and typically got 1-2 new plugins per year (call it $50 total value) and the latest Mixbus and Mixbus32C free from v4 through v10 for free.
Now I join the ranks of just paying for MIxbus Pro version updates as I am on the SSL subscription, which includes all Harrison and Slate plugins. I'm sure they up the sub price one day (I venture to say it will happen in 2025) but for now I pay the $14.99/mo that I was originally paying for only the Slate sub.