I'm eager for an answer to this question too. I plan to only machine aluminum plate. I want to do custom faceplates for pc-cases (a product I'm developing for which I use an oem pc case). I have no experience with the gear involved but I'm proficient in a few 3D apps.
I wonder if it's smarter to farm the work out to some of the guys on these forums. I'll end up needing batches of 10 or 20 of these 12"x12"x1" plates. with the "mini" mills like the Taig (usually go for $1000-2500 on ebay) I'd have to make smaller plates to bolt on to the case, which is fine.
Any advice is appreciated.