Would check into CFL bulbs, and reading some Grow Logs.

If you are handy with wire-nuts and electricians tape, WalMart has adjustable (they swivel) outdoor security light bases, ($8.00 or so, holds two CFL bulbs) but you have to wire it to an extention cord. I fastened three in a row, on a 1 x 8 pine board (18" long) Works great for my veg closet...but nothing works for flower like an HPS. With the HPS tho, likely you'll have to vent the heat.
Here's a link to see what my CFL unit looks like:
http://boards.cannabis.com/advanced-...ml#post1830094
You'll need to cut-off the female end of an extention cord, and splice it to the light bases, but it's an easy task. If doing this...get a cord that's long enough not to have to use another extention cord, lol. A couple of hook-bolts to screw-in and hang the board helps bunches, too.