There aren't any yet. USB-C is a new standard, and requires a lot of complex circuitry to work right. Most of what you see advertised on Amazon are just USB 3.0 hubs that have USB-C connectors attached to them. Unfortunately, they cannot reliably charge the MacBook, or in many cases provide more than USB 2.0 speeds.
That's why the KickStarter projects like Hub+ and Kadi Port are all significantly delayed. The most descriptive so far has been HydraDock, who has a very detailed explanation as to what is going on with their project (though they basically accuse the other projects of being scams).
There was/is some suspicion around Hydradock, as well, though they appear to have a professional website with names, pictures, and a real address, and have been a lot more transparent about the issues. That said, you might want to wait until one of these companies actually has a shipping product before committing any money.
https://hydradock.backerkit.com/hosted_preorders/project_updates#preorder-nav
It seems Apple is one of the few companies who had working true USB-C devices. They probably have monopsony buying power right now and left little for anyone else. They could have made some decent sales had they made a dock of their own, but I'm guessing they view that as incompatible with the vision of the MacBook.
