Just had a quick look on ebay and found these which are similar to the ones I use -
http://www.ebay.co.uk/itm/16CH-Wirel...item20cddc3dc2
that set has three receivers and one triggger for £24 with a single receiver they are a chunk cheaper.
I wouldn't have thought that a shutter speed of 1/125th would be causing the issue, I assume you setting the camera and the flashes manually?