I used to have a link to a manufacturer, who I am pretty sure was based in Austria, who would supply the basic machine to your spec, ready for a CNC conversion.
You could select a few different sizes of machines (IIRC the biggest mill being around X3 size), and they had options for dovetail ways/linear guides, along with acme or ballscrews.

The website was pretty basic, with only the basic details listed, along with prices.

Does this ring any bells for anybody?
I've tried numerous searches, but I've so far not found the site.