A general rule is 150 watts per plant if you're going to flower with CFL's.
For you to effectively veg 1 plant I'd suggest (4) 26 watt , 6500k(blue spectrum) CFL's. This will give you 6400 lumens to veg with. (approx $20.00)
Switch your bulbs to (4) 42 watt, 2700k(red spectrum) CFL's for flowering. This will give you 10,800 lumens to flower with. (approx $36.00)
Other costs will come from how you choose to build your CFL fixture.
Remember with CFL's that bulb placement and proximity to the foliage is the key. Good luck.