If you find any of the following useful... rep(green '+' spot) would be appreciated.
If you can only get one CFL bulb type, make it 5000k(called: full spectrum). It's balanced for both veg & flower. 2700/3000k(called: warm white) is the 'peak' for red spectrum growth. Around 6500k(called: daylight) is 'peak' for blue spectrum. They're best mixed no matter what you use. You're best off getting lower-powered(~42 watt or less) 6500K bulbs, as they're primary veg, which takes half the amount of light, basically(unless you grow them HUGE). Getting higher powered 2700K or even 5000K bulbs will promote better blooming and even spectrum.
Or get a T5 set-up! Ballasts are around $50(inc. tax/shipping) that can power two 54w(once 54w bulb = ~150W HID equivalent, at 1/3rd power). So for $50 + $20 for two bulbs. $70 for 300W HID equivalent! Under $140 and you could do very near the equivalent of 600W(2.8x) HID, which would also cost you twice much up-front, and power usage? A mere 216W(4*54w)! Neither includes ballast consumption, but that seems minor!
Plant-specific LEDs claim nearly 99% PAR, and as such are ~2.8 times more efficient than HID(and costly). Technically CFLS can get up to 2.3 times as efficient as HID; however, most CFLS are 1.7 times as efficient or 'better than' HID.
UFO lights, 90 one watt LEDS, claims equivalent to 600W HID at 2525 lumens (6.6 times)*. Some are several hundred dollars(avoid). The claims sound somewhat outrageous. 13.8w=118, 48w=1224, 90w=2525 lumens
Then there's this site:
http://www.enviro-gro-lites.co.uk/stuff1.asp
100% PAR, CFLs, if the claims are true(it makes the LED 90w=600w HID story smell of bullshit) the 250W CFL bulb(author statesL 3-4 cm away w/reflectors... maybe he meant the 125w bulbs? ambitious!) would to be more plant-friendly(PAR) than a 400W HID(as compared to a 220-350W 'regular' CFL).
NexStar claims their 220W 347V (Canada) is 400W Metal Halide equivalent
http://www.nexstarlighting.com
*all link for references only! This last one is probably bullshit, so don't say I didn't warn ya...
http://www.thelashop.com/product.php?productid=391
If you did't know, HPS and MH top out around 35% PAR(brand new), and degrade in PAR value quicker than mere lumen output(HID400w@50k lumens = ~17,500 PUR). Other bulbs also degrade over time, but not nearly as quickly. If what the 100% PAR CFL guy claims is true... 140W CFL would be equivalent to 400W HID. At around just over 1 inch away... vs 1 foot for HPS... I might have to believe him.