MacBook – Apple Thunderbolt 3 to Thunderbolt 2 and Thunderbolt Display

I have recently run into a similar situation as yours. Both of the proposed solutions below do not use expensive gear like thunderbolt docks or monitors, and can achieve the same (or similar) desired end result.

1. This Thunderbolt-to-Dual-HDMI adapter allows your to connect two 1080p monitors to a single Thunderbolt port, and have both those monitors act independently from one another (ie. they are not mirrored). The adapter is also passive, which is nice.
2. Buy a Chromecast. This solution is sub-optimal, and is dependent on you having a decent internet connection, but with this $35 device, you can stream a browser tab, your desktop, audio, video, and more to an external monitor. The third monitor can then be added with a simple Thunderbolt-to-HDMI adapter.

What you need is a Displayport/DVI/VGA port and a displayport/thunderbolt port and since it seems you don't have a Mac with a second Thunderbolt port you will need to get something that will give you two Thunderbolt ports.

Once the question is framed that way (?) then it seems to me that the choice is one of the Thunderbolt "docks" that are often sold as a way of connecting a MacBook to numerous ports all at once via Thunderbolt.

There are numerous examples of such devices out there but you may end up with a lot of ports you don't need (USB, Ethernet, Audio, SATA, etc.) depending on which one you decide on.

I am not aware of any devices that are the Thunderbolt equivalent of a USB hub but perhaps other folks might know of something.