Welcome to the forum! Enjoyed watching the video - you've enlightened me, I had no idea that you could get bespoke frames - although I feel slightly sorry for your arms with all that filing!

I think if I were you I'd be looking at small used machines aimed at the pro-hobbyist / small production, something like a little Tormach, or an older Boxford from a college, or alternatively a pre-converted (or converting yourself) mini-mill (Sieg X3 or similar). All of these would nicely fit into your working envelope, and give you plenty of scope for more materials in the future.

I'd be keeping clear of the 'maker' type machines, X Carve / Shapeoko / Workbee - after having read up on machine design for a while, none of these strike me as particularly well thought out, and they don't appear to be using high quality components. I wonder how many of them will be around in five years time. Having said that, by making CNC affordable and accessible, they have gathered a decent following... Maybe I judge them too quickly.