new to fluorescents. how much light?

so aside from my primary grow, i have a little extra space thats about 2x4 by a little over 3ft high... obviously i cant grow with HID's, nor can i grow any sativa's or really any normal strain for that matter. as far as i know, about the only thing i can grow with this limited hight is an autoflowering lowryder strain under floro's.

I read here on rollitup that plants prefer around 10,000 lumens per square foot during flowering, and each 54w T5 bulb puts out about 5000 lumens. that would mean that i'd need something like 16 four foot 54w T5 bulbs for my little space. Aside from shelling out a fortune, i'd imagine i'd run into serious heat problems from the fixtures alone, (nevermind the bulbs) thereby eliminating possibly the only significant advantage of floro's in the first place. If that's the case, why the hell does anyone really bother with CFL's/FL's at all when you can get a complete 400w HPS setup for $120 that does the job just as well as $1000 worth of FL's???? and I've been hearing for a while that FL's and CFL's were great for "budget" grows. I'm confused.

I Think CFLs are great if you only intend to grow a few plants. After that the clutter and cost per lumen out weighs the intial cost of the 400w mh / hps setup. With just a few small/ mid sized plants you can easily stick to 100w per plant for veg and 200w per plant for flowering though.
I think people choose CFLs for a few reasons.
such as Limited space, the initial cost to get started, and the versatility to put them almost anywhere around the plant.
their are probably a few other reason as well.
CFLs deffinantly have their place in low budget growing.
Check out my CFL grow with tons of pictures.
https://www.rollitup.org/grow-journals/127795-homemade-100-grow-box-2.html
check it

how about large cfls

i like the idea of super small stealth grows, but thats about the only situation where i see a place for FL/CFL's. the cheapest 150w CFL i can find is 60 bucks. it looks like you have 3 of them. insidesun is selling a complete 400w HPS system w/ballast, bulb, wires, reflector and 3yr warranty for $99. from what i understand, 400w HPS produces a lot more usable light than 450w of CFL's and is almost 1/2 the price. thats why im confused when everyone says FL/CFL lighting is better for budget grows. where i'm standing, its a whole shitload more expensive...

Cfls are usually favoured by new growers as they are easy to setup, requiring nothing more than a standard light fitting, they are cheap (for small numbers of them), and allow for smaller grow spaces since they can be kept within a couple of inches from the plants and don't normally require cooling.
They aren't really suited to larger grows due to the sheer amount of bulbs required to grow more than a couple of plants to any decent size, and they are really not very efficient when compared to HID lighting. Cfls generally kick out between 60-70 lumens per watt, MH are about 90 lumens per watt, and a good HPS will produce up to 150 lumens/watt, just quite a bit more heat as well.
In a 3 foot high growspace you might be able to get away with an econolite or 2 (the $20, 150w hps everyone seems to be getting these days) if you DIY a cooltube from a bake-a-round it should be manageable, I don't have personal experience of how hot these bulbs get but if I can cool my 600 hps like this, with a 240cfm fan, I'm sure you can work something out. It's either that or surround the area with cfls, and leave the ceiling free for the plants to grow up to...
It's quite possible to grow indicas in that sort of space, I'd scrog 'em and have each plant take up a 2x2 area, as soon as you have them woven nicely into the screen but before they get a chance to turn back up, 12/12 the bitches and see how it goes. You could get at least a couple oz per plant with a 150hps above each one.