I've had one of the Pixel TW-282 TIMER remote models for years now, used at Astrofest a few years back it would work from the kitchen to my rig adjacent to the h0ughmahal.... FWIW the unit wasn't the least bit affected by WiFi signals. I had intended buying another unit as I believe that one Tx will trigger multiple receivers allowing 2 cameras to be triggered consecutively.
http://www.pixelhk.com/Proshow.aspx?id=299
Review here
http://www.thephotoforum.com/threads...review.249753/