MacOS – El Capitan and Daisy Chaining

Unfortunately, it is not possible to daisy chain displays through Mini DisplayPort.

However, there is a company called DisplayLink that makes software drivers for USB video adapters. They also have links in their store to Mac compatible, DisplayLink approved USB display adapters. One of my coworkers uses this to connect a MacBook Pro to two external displays and a TV in his office. It uses the extended desktop feature for each display. It's a pretty sweet setup and works flawlessly.

I see no reason why this wouldn't work for you. Good luck!

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.