The most common Compact Fluorescent Light would probably be the 23-26 watt bulb. You typically want "cool" bulbs, in the 5000˚K-7000˚K range. The most common for vegetative growth would probably be 6500˚K. "Warm/Soft" bulbs in the 2700˚K-3000˚K range are good for flowering. You really want to consider the amount of light you bulb puts out, measured in lumens. 23w CFLs tend to be the most efficient lights to use in so much as they put out the most lumens/watt. You may want to consider using a mixed-spectrum light set up like 3 6500 and 1 2700 for veg and the opposite for flower for each plant. You shouldn't have too much trouble finding these types of bulbs at any hardware store. Drug stores may even carry these types of bulbs. Just make sure you read the temperature and lumen ratings on the package and you'll be all set!