First, if you a dedicated to using floros, get some t-5s.
Second if you're not dedicated to floros, do get an HPS. For the price you'd spend on enough CFLs to fill that space, you could probably buy a good HPS. Don't forget you need twice as many CFLs: One set for veg and one set for bloom. I mean, sure you could get lots of little ones for cheap, but it still adds up. At Walmart (EVIL!!!!) a six pack of 23 watt CFLs cost $20. You'd need to spend $80 just on bulbs to get even close to one 250 watt HPS. Then you need to buy all the accutraments and stuff such as sockets, cords, etc. Sure you could probably get all you need for $100. But you can find a decent HPS for only maginally more which comes with reflector, etc. And when you have 12 CFLs in that space, the heat isn't really going to be any better than one HPS.
Third, if you are still dedicated to going CFL, don't waste your money on getting high wattage CFLs. Stick with the ones you can buy locally. I have had nothing but problems with the monster CFLs I bought!
BTW, I mistyped bulbs in the Walmart search engine. I typed in "Light Bubls". You know what Walmart offered to sell me instead of light bulbs or even telling me no results? Bibles. That's right. I got more than 100 hits for light bibles at Walmart.