Brenda, My husband just finished making a canopy for my 55 that will hold 4X110W VHO lights <img src="graemlins//angel.gif" border="0" alt="[angel]" /> I got the ballast (electronic), endcaps, wiring and bulbs from hellolights.com for ~$240. My husband figures he spent ~$30 on wood for the top, using luan (sp?) plywood and 1x3's to make the frame. it didn't take him very long and all I have to do now is sand and slap on the polyurethane and then let there be light!
One suggestion, if you do go with the VHO kits, get the 46.5" bulbs instead of the 48" ones, it will be much easier to fit them into the canopy. We also left the back open to help dissipate the heat. HTH