I must be missing something: https://i.imgur.com/3PNqSt5.png
Edit: You're talking about spaces[1], I'm talking about volumes[2].
In digital ocean, I believe you get a volume for free with your $5/month instance/droplet (it's not added separately, which differs from most other cloud providers).
The screenshot you shared is attempting to add additional volumes to a droplet. See the pricing for droplets, it includes 25GB of SSD and 1TB of transfer.
For $5/month you can get 250GB of storage with 1TB outgoing.
Additional is $1/100GB and $10/TB