eBay
Radio Popper PX Radio Camera Flash Receiver with Nikon mounting bracket and stand plate. 

The most reliable photo strobist radio transmitter/receiver system on the planet. The best rating. See plenty of youtube videos.

Great distance coverage more than 100m, cross platform, 1/8000 of sec sync. Always fires, not like the cheap radio systems with % misfire. Radio Popper is 100% reliable.

We have 2 radio transmitters too if interested, plus a back up antenna, plus on camera bracket.

NOTE: before to buy please contact us as we've listed them as a kit in another listing.