Cannot Add Beast Master in DnD Beyond to Ranger

Quote from OgmaDorus >>

"you can just buy that for $2 and it’ll even count as credit if you later decide to spring the $30 for the PHB here too"

- is this still available somewhere? I cannot see this option to buy only one subclass.

 I am 90% sure they removed the option to purchase individual subclasses. it lasted for a few years but they changed the sales model. 

Quote from OgmaDorus >>

"you can just buy that for $2 and it’ll even count as credit if you later decide to spring the $30 for the PHB here too"

- is this still available somewhere? I cannot see this option to buy only one subclass.

No, that functionality was removed from the marketplace last year. It's now only possible to buy entire books.