Interestingly, I have both a plastics supplier and aluminum source that are a lot closer than my MDF supplier.
I've been spending a little bit of time this afternoon looking at what kind of computer I want to run this. What's nice is there's a fairly new-to-me device out there that negates the need for a parallel port and it works awesomely with Mach 3. It's called a SmoothStepper from Warp9 Tech Design. There are two models: one using USB, the other Ethernet. If I want to use a more modern computer, this is a nice find.
Now, I do have two older machines - one a Pentium II-generation Celeron, and the other a first-gen Athlon - and either one should (theoretically) be good for running Mach 3. Trouble is, I'd rather not have either one of them anywhere near the dust I'll be making. I'd much rather have something passively cooled and doesn't have any moving parts. So essentially, I'd want a PC that looks like a big heatsink running an SSD. (One of those new Intel NUC motherboards with an Akasa Eula case would be perfect.) There are a lot of candidates for this, with more and more as time goes by, so I don't have a limited choice.