If you are not in a hurry, you can probably find one via Craigslist or the equivalent. I must have seen fifteen or so in the Bay Area (CA) over the last few years (and bought two of them...) and I was actively looking only for the shorter ones because I don't have much headroom. The nine-footers seem to be more common, but that is nothing that a hacksaw won't usually fix. They are usually not considered shippable due to the very considerable weight, although they all come apart into smaller pieces without much trouble.
The Cambo/Calumet style with the gear-driven crossarm is the cat's meow. My guess is that it will handle considerably more weight than I would dare put on my Majestic gearhead, and I doubt that capacity will be an issue with anything other than the Arkay or Calumet medium-format designs (which, by the way, I don't think I have ever seen offered; I wonder where they all are?).
One thing to consider with any of these stands is that you will need a decently smooth, hard floor for them to work easily. Even though they are extremely stable, there is also lot of mass up high so that on a soft or rough floor you need to push the base around rather than just hauling on the crossarm (when the crossarm is at mid-column, so is the counterweight...).
Another, possibly minor, point is that there are several gearhead mounting styles, and the higher-end stands use adapters of various sorts for camera mounting. Unless you find a stand that is in current production, you will probably want to use the mounting that comes with it, so it may be important to make sure that a used one has all (or at least, enough) parts present.
I hope this helps; with any luck, someone with more professional experience will also chime in.