If you are going to fasten the boom arm to the table, I would save the money, assuming you don't have one already, and make your own. The setup that I use works just as well as the boom, if not better and cost about 20 bucks. The only advantage that I can see for the boom arm above the homemade version is the fact that it is swivels. But if you are going to mount it on a table, you can build in a swivel quite easily.
The setup is a piece of PVC electrical conduit, the grey stuff, with a sweep fitting at the top so it has an "L" shape. Rather than use the boom arm as a way to suspend the hose as the Festool version does, I actually run the suction through the conduit. I use a no-hub plumbing fitting on each end to connect the conduit and the hose. This saves you the expense of the boom arm as well as the extra hose that you usually need to make up that length. You can get a short section of regular shop vac hose to run from the lower end of the conduit to the dust extractor. The ridgid fittings fit the opening on the CT-22 perfectly. For the swivel, though you really don't need one, you could cut in two couplings on the conduit about 2 inches apart that would act as the stops. Then you just use one of the "C" shaped conduit anchors in between the two couplings to mount it to the table. Mine works as well or better than the boom arm as the smooth walls of the conduit have much less friction than the hoses.