No more do you need to spend thousands on DSLR wireless transmitters.
You can get a USB wireless kit with receiver and transmitter then connect the transmitter to your DSLR via mini USB to USB female adaptor or whatever your DSLR USB output is. (My Canon 7D outputs in mini USB and Canon Wireless Transmitter costs hundreds!)
Of course, this author went even further, soldered the pins into a weather-resistant plug, and voila!
This hack should work for all types of cameras including point-and-shoots and camcorders that use USB.