G Suite - Can you have Basic and Business users in one domain?

Can you have different users from Basic €4,- and Business €8x,- in one domain?

In general you can add and delete users in G Suite as you need. The cost is always per user. Unfortunately, it is not possible to add users from different tariffs. Depending on the option you will decide to use, that one will be applied to all users.

Please find more about G Suite in general on this page.