if you add up the cost of fixtures, cfl's and fans for cooling your looking at 100-150 dollars. I dont have Lowes here but im sure they carry some form of security lighting, look into it. They come with a ballast. (By the way you might have to wire your CFLs anyway).
Heres how you wire a hps..what you need: HPS, 1 heavy gauge extension cord, and two wire cap thingy's
open the box and look at the light. there should be 1 white wire 1 black wire and maybe 1 green wire or bare wire
Cut off the female end of the extension cord.
Attach the white on white and black on black, screw on the cap thingers.
Some lights are diff so next attach green on green OR there may be a green screw on the light fixture, feed the green wire from the cord to the screw and screw it down.
Thats it, plug it in. Like i said you might have to wire up fixtures for CFLs anyway.
Cost was roughly the same for me and heat is no longer an issue
Pic 1 a security light Pic two the extension cord wiring