What watt CFLs are you reffering to? If you are getting the big ass ones and can only afford one then make it a red one. The 2700-3000k one is best for flowering but will work just fine in veg... Also mixing the spectrums together (warm and cool CFL) works great.
The plant isnt vegging and flowering at the same time... like bob said they veg for 2-3 weeks and then start flowering.
You can always get an air cooled fixture for an HPS and a fan to suck the heat out but that can add up.
Is this your first grow?
DISCLAIMER: everything I post and say are lies. I am simply roleplaying. All photos were found on the internet and/or fake!! I do not grow or use anything illegal.