RuneScape: Dragonwilds

The game currently does not contain any additional purchases beyond the base game, which is priced at roughly 30 USD. The game is currently in early access, so that might change in the future. On the Steam page they state the following:

We will not be charging players for updates added to the game during Early Access, but may release post-launch content as Paid DLC in the future. For now, our priority is making the most of our time in Early Access!

Purchasing the game during the early access period grants the player cosmetic content in the form of a scarf, cape, and tapestry, as well as music from the game.