I think people use as low as 3 of those 23watt cfl for the computer grows and when they do it right pull 10-30 grams of some good but you could really "flower" with any wattage i guess lol
I honestly think you could get away with less wattage and a higher yield with a cheap led. The mars 300 sells for $79 on ebay. They're about 170 watts. Here's a dude getting 4.2oz's off of one plant with it. PlatinumLED Mars-Hydro comparison grow You'll spend almost near $79 on 3 nice CFL's with a light fixture. The bud you have in the end won't compare. CFL's veg good but it's hard to beat these cheap leds for small scale. 400 hps setups are down to near $100 now. It's a good time to get one. Not exactly CFL micro wattage but people have built some small setups with 400 watt MH/hps hoods and they put out lots of dank bud unlike the small cfl setups I've seen.
I've seen some pretty good square foot micros grows with about 100w of cfl in them(ie, blynx @ icmag)...producing about 1.5 - 2 oz per run. A really good run with cfls seem to get about 1/2 gram per watt. I run a small square foot cab that was lit with 5x 13w led bulbs and was able to pull about 2 oz out of it consistently. That's about 1 gram per watt..I've been having really good results with those 13.5w led bulbs though, cept they coast about 10$ each. Just try to figure out your goals and do the math of how big of an area you have to work with and how much light it need to get great results. imo - 100+watts per square foot of cfl's , 60-70w psf with led bulbs/panels, 50w psf with hps, 35w persquarefoot with cob leds. Alot depends on your budget and diy skills. Just make sure to use enough light for your area. ...for example 100w of cfl over a square foot will produce great results...but that same 100w spread over 2sq feet will produce alot of fluffy buds and reduce the overall yield and quality.