This is interesting:
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Maybe I should just make one myself. I ran across those pics on a machinery clearance site, from the UK if I remember.
That looks like aluminum, I'd probably at least do 1018 and maybe even make the top table a t-slot table. I've got the tooling for it already. the big plus of making it myself as I can size it to my particular mill. As short or as long as I want it and the holes/slots where I need them to fit things like my rotary table, clamp kit, etc. My benchtop mill has roughly 13" of vertical clearance, so I shouldn't have a lot of problems fitting it under the head. Of course, making it myself means I can make it shorter if needed, although at the cost of tilt angle.