Asset Store

You can obtain anything exportable from Unity from the Asset Store, like editor extensions, scripts or 3D models.
Those assets can be free or paid.

This tab has an integrated download, that means that you can download the assets directly to your unity project, without the need to use a browser.

The assets are licensed per-team, so you don't need to purchase the same asset for each team member.

The assets are free to distribute in games.

Cheaper than hiring a developer/artist.