Try here. They have the 400/700 watt (8/4ohms) versions too, just not listed. I'm crazy about similar class D amps, have 2 Bel Canto S300s.
DIYCable.com : Intro » Home » Exodus/Hypex Amps » Exodus Amps
Design:
Hypex Electronics B.V.
Look at Ucd discussions here:
PSW Recording Forums: Brad Blackwood => Favorable Hypex amplifier review... diyAudio Forums - Class D
Good luck.