where are you gonna have the lil box at? if it is gonna be kinda out in an open area, i would say you could get away with one oscilating fan on all three of them, as the cfls aren't gonna get all that hot really, so there isn't really a need for three seperate fans..
i would try it out with the one for now, and if you notice that you start having probs with heat or what not, you could always get like three small computer fans, one for each " unit", and see how that goes..