I know you say 400-600w... but I have a 250w MH fixture.... It is a Sun Systems "Garden Light" with safety glass over the bulb, built in ballast, European reflector material, 8' grounded power cord, and backlit on/off switch (black housing). It is 24" x 12" and I have the hangers... somewhere.

I had used it over some Sarrs for maybe 5 months and other than that it has been sitting in the corner of my room... PM me if that interests you.

Andrew