Normally $100, $50 on sale. Some compatible brands other than Canon are available.
I have an earlier modelof the Shutterboss and it works great. On my model range is specified as 75 feet but it works fine at about 100. I set up the camera on a tripod, 8 to 10 feet from a bird feeder, and fire away from in side my house.
This model by the way has a specified range of 250 feet.