It's always interesting to see how you can ask simple questions that are simply not to answer.
If I am to help you answer this question, then they'd have to tell me what is their actual task. Through a study of literature they may be able to specify the process parameters and then you still have the problem, that most manufacturers do not reveal important process parameters. Then you can but for users, particularly in universities, ask.
Casually it, a cheap machine to buy, and on the basis of wanting to achieve a result. The most serious problem is then to develop a new process-energy-source.
Before even created a stronger competition, is the question of what I want to do. It may first be asked completely safe for pure teaching, technology development for EDM or WEDM, developing their own modules for special applications. In the first case, a simple system is sufficient at all functions are adjustable by hand, ie Parameter dependencies can be determined. In the second case, a high-quality investment should be purchased, but in which all parameters can be varied according to your own imagination. This is especially true when operational demands are to be determined. In the third case, the system itself must be completely assembled or the machine must allow that assemblies are interchangeable. Since consultation with the manufacturer should be possible.