In case you want to control the DC only (i.e not blast gate controls), I got a cheaper and possible better version. Get an appliance rated X-10 switch (either for 110 or 22oV-whatever you have) plug or wire DC into that, get an x-10 receiver (will plug in on any 110V receptacle) and then buy a couple of x-10 pocket remote (look like key chain remotes).
That's what I have for my dust collector and rotary phase converter.
A box of key chain remotes (6 of them) on ebay runs about $10-15, appliance switch (from x-10, smarthome.com or ebay) runs about $15-25, x-10 receiver runs about $15-20.
All of the items can be had on ebay (least money), x-10 web site, smarthome.com, or Radioshack and the like (most money).
If you need exact model numbers/descriptions let me know.
Nice thing about this system,: cheap , no wiring, easily available and very rugged.
Bernhard