T5s, ballasts, reflectors - reefgeek.com
VHOs - AtoTlamps -
http://www.atotlamps.com - a local light bulb store, but they are on ebay too and ship nationally. You can just call them up, they are very helpful. They make their own brand of VHOs and these things are light years ahead of URI or Coralife - both color and intensity. Ultra bright, can't really look at two 110 watt bulbs if they are side by side. Price is $17 per bulb, ridiculous. I dislike VHO but in this case it seems to work wonders.
Everything else - Home Depot, Lowe's.
--Nikolay