The DC motor controller market is very dynamic. Here are three new motor controllers ready for big robots.
Motor Control, Brushed DC, 1x40A, 7V-30V,32 bit microcontroller | US $174.95 + $7.36 shipping
This is a single channel motor controller that it fits in a very compact 70x70mm board. It features a 32-bit microcomputer, a single 40A output, and capable of operating at a voltage between 7 to 30V.
You can build something big with this motor controller. It is capable of a 20A rated current and a peak current of 50A. It is a dual channel motor driver with dimensions of 11cm x 5.8cm.
GERTBOT – Motor/power controller board | About US $60
This motor controller is compatible with the entire range of Pi family: Model A, Model A Plus, Model B, Model B Plus, Raspberry Pi 2. It features its own CPU designed to control the DC motors without the help of the Pi board. Is has four H-bridges that works between 8 and 30V. You can configure the bridges to work for two DC motors with 5A per channel or one DC motor for 10A on the channel.