What are you planning on doing with the machine? What state of conversion are you planning?
I think the DMM setup is very well put together and comes complete for electronics. If I was starting id be looking there.
Also, I didnt realize how touchy Mach 3 is. Flashcut is close in cost once you really start adding things up. I might end up there anyway. Its worth review if you need a reliable machine.
Your list is the basic blocks, but there is alot outside of that, im still ordering crap all the time. Bearings, loads of hardware, wire, tubing, dont forget the oil system.
I tried a computer case, it was no joy. Go with a NEMA 1 enclosure or something similar, you want a big metal box, not something for modular computer or server parts. That was my experience.