I am trying to design a cheap educational kit for teaching control theory and I am thinking to provide the students with a motor to use for some simple closed-loop RPM control and possibly something related to a pendulum. I like the TT Motor with Encoder (6V 160RPM 120:1), SKU:FIT0450, for this purpose whose price, at $7.40, is hard to beat. The choice of controller and motor driver is a little more difficult as there are many choices. I am leaning towards the Romeo - an Arduino Robot Control Board with Motor Driver, SKU:DFR0004, which at $29.50, considering that includes both the controller and the driver, it is quite cheap. I understand thought that that is an old board and that newer versions (more expensive) are available.

Again, price is important (I would need to buy at least 50 of these kits) and I don't mind working with an older board, as long as it works properly. Does anybody have any advice or suggestion on this or an alternative choice for a controller board and a motor driver?