Somehow I missed this thread. A coworker got set up with a pretty sweet standing desk set up from COI at home for about 2k which included filing cabinets and a loaded Aeron.
I was not in that same ballpark budget wise, but was able to get a refurbished Mirra (1) with all Options for $400, which I am happy with. I think the term "refurbished" is a bit generous, in the sense that the back piece had a little bit of surface 'coloring'. It is white in color and was looking a little "grey" in spots, but worked it over with a magic eraser and seems to have helped (probably should add some protectant at some point). Otherwise though, everything else looked fantastic. Very happy with my purchase. I was actually having some pretty serious shoulder and arm pain from using a dining chair. Even crappy office chairs are $200, so I don't mind spending the extra for a BIFL mindset. I find it more comfortable than my Aeron at the office.