I pay just about $20/month for 2 select subscriptions, one of which gives me $100 at the end of each year so I can pick and choose what I want to own (Kilohearts, btw). The is not a true 'subscription' per se. It's my plugged in membership with Harrison. That monthly membership fee does get me anywhere from 1 to 3 free new plugins a year and goes toward supporting Harrison's dev effort (as well as purchasing major version upgrades at a reduced cost).
I'll succumb to Slate's subscription when I get a project that uses his version of ANA or THU but only until I can convert the projects to my native versions of the products. As of right now I do own all of Slates plugins, so it's just that niggle that opening a project that uses Slate's ANA or THU will not recognize and load the actual native plug and populate his settings (stoopid, stoopid, stoopid even though I understand the reasoning).