Shure QLX–D 4x rack unit receivers. $400
Four receivers in a 3U roadcase with power and antenna distribution.
Shure's new generation of digital radio frequency gear has a far better bandwidth allocation system so you can run more of them at once without interference.
A choice of transmitters:
1. belt packs and heasdsets mics,
2. belt packs and clip-on lavalier mics,
3. handheld cordless SM58 mics.
See the video here.