Simple Stepper drivers

I am building a reaction course for airsoft.
The initial problems are solved and I am now standing with a working prototype using Adafruits Arduino Motor Shield.
The problem with this it uses alot of I/O on the arduino and it is a quite expensive solution.

I need a simple schematic for a stepper driver which is controllable with as few signals as possible from the arduino. Hopefully one or two I/O's. I'm thinking something triggered by a relay apparatus.

I've searched around and couldn't find anything on the subject.

and it is a quite expensive solution.

Any more integrated solution is likely to be even more expensive. We are talking about one off pricing, often a mass produced system is much less expensive than a fraction of the parts that make it up.