Hi,
it would help to know more about what you want your machine to do.
You have said it does not need to be big. Big machines are vastly more expensive than small machines.
Are your keyboard kits flat or nearly so? This will have implications about the Z axis travel for instance.
What materials are you using?. Plastics and wood do not require a hugely stiff machine whereas brass and aluminum require a much stiffer machine,
and if you need to cut steel....then multiply the stiffness by ten....and the cost by one hundred. So the materials you want to cut will determine how stiff,
and to a large extent, the cost of the machine.
How fast do you need to machine? If you have high volume requirements then you will probably require an Automatic Tool Changer, at considerable cost.
If the machine is required to move very fast then you will require servos rather than stepper motors....and you guessed it .....servos cost more.
All in all you need to very carefully consider what you want your machine to do. It may be for instance you want to be able to cut steel....but that will put the
price up hugely...and so you may have to forgo what you want and focus on what you need.
Craig