No disrespect intended but I think you need to get yourself to a workshop that uses CNC routers for a day or two before making any decision.Doesn't matter what brand they run,just see what is involved in booting the machine,homing it,holding the work down,establishing the tool length and the part datum.Make sure you have a full grasp of all of these matters and then learn how to stop a program that looks like its going wrong and get the tool out of the job.
Then spend a day or two playing with Aspire,if thats going to be your software of choice.I believe there is a trial version that can be downloaded.Get comfortable with the process of creating vectors,ensuring that those which need to be joined are in fact joined and then move on to creating toolpaths.You need to be able to select the tools to do the job and describe them in the tool library if they aren't the default tools.This will involve setting speeds and feeds and if you get it wrong there could be smoke or broken tools.Slow down the simulation and be certain that the machine will do what you want it to.Find the right post processor and use it to create the program and then decide on how you transfer it to the machine.
Once you understand all of these facets of machine operation,you can apply your knowledge to the purchasing decision.Beware of people who have bought a particular brand of machine and who tell you how great it is unless they can show evidence of having made a thorough comparison with other machines. Merely having a machine in the garage that does stuff they couldn't do previously seems great,but is there another machine that could have been greater?Simply by coming here and asking the question you have demonstrated a desire to progress along the path.Ask detailed questions about each and every operation that you will have considered and don't try teaching any of it until you are absolutely certain that the outcome of pushing the green button will be what was intended.And don't forget to tell the students that a machine doesn't know how to tell the difference between flesh and wood.