The Teclast brand is certainly one I’ve heard of, since they make solid and affordable tablets. They also make dual boot devices, like the Teclast X80H model, shown below, that somehow was turned into a triple boot unit.
This product can usually run Android and Windows 8.1, but apparently it can also run Ubuntu. Teclast X80H is at its core a dual boot Chinese tablet, relying on the famous Intel Bay Trail-T processor, clocked at 1.33 GHz and 2 GB of RAM. It also has 32 GB of storage and an 8 inch screen with an IPS panel. The usual WiFi connectivity is here, plus Android 4.4 and Windows 8.1 as the OSes.
The price tag is a mere $100 for this product, which is very appealing. An user of the slate managed to get Ubuntu on board, as shown in the picture above. The user is relying on Ubuntu Lite via a plugin solution, that also seems to involve a mouse and keyboard. The Ubuntu version shown here is the desktop one, not the mobile one, that would be a bit harder to install.