Buy a StepFour 540 Basic.
It's not only the machine what counts, but much more important how user friendly the software is.
When you're making and trying bulkheads you want to make small adjustments as easy and fast as possible.
All the rest is just discouraging your creativity. And the result clearly shows the difference.
It's maybe not the cheapest choice but definitely one you will not regret.
I have mine now for some 12 years, spent already thousands of hours on it, it never let me down and also their after sales service is prompt and first class.
I had also CNC Sherline tools (metal parts), CNC Haase (foam cutter), StepFour CNC Foam Cutter... but StepFour always is a class on its own.

Nicolas.