2000 lumens/SF is a pretty standard minimum. If you have everything already and just need a bulb, look up a lighting/electrical shop. The bulb is the easy part, I meant that getting a fixture for growing isn't as easy to put together at those places.
Also, cfl's with higher than 125 watts usually require a larger socket size than the standard size. May need a mogul socket adapter if you're going after that-it easily allows you to put the bulb into a regular size socket (they're relatively cheap).
Online check out 1000bulbs and littlegreenhouse