"Per plant" isn't a very meaningful way to measure this, since plants can vary in size from 9 inch tall autoflowering dwarfs to 15 foot tall Sativa "trees". Needless to say, the lights you'd need at either end of that size spectrum are going to be different!
Also the "watt equivalent" rating of fluorescent bulbs in comparing them to incandescents isn't a very useful measure here. Forget that.
I think for fluorescent lighting, 70 watts of actual power draw per square foot is probably a good rule of thumb, assuming you're dispersing the light right with reflectors and are starting with a good spectrum. You can get away with less, but at the cost of somewhat lower yields.
So if you're trying to evenly and properly light a grow space that's 3x7x6 feet high, you'd be lighting 21 square feet of area, and would require roughly 1400 watts of CFL, or say 60(!) 23 watt CFL bulbs. Note that this implies that your efficiently using ALL the space in that area. With only three plants, you may not be. When your plants are just seedlings or small, then again, you won't necessarily need to use the entire space and could scale down.
But needless to say running literally dozens of CFL lamps is not practical, which is why nobody uses CFLs for big area grows like what you're describing.
If you really want to fill a space like that, you're probably going to be much better off with two 400 watt HPS lamps or some other good HID lamp combination. If for some reason you're against HPS lamps, then you'd probably want to use conventional tube fluorescents, which are going to be much easier to install, handle, and manage.
