Aren't CF bulbs in standard sockets the most cost effective way to go for smaller tanks? I mean, I can fit 2 75W equiv CFs for about $6 for 150W on a 20 Gal and replacement is about every 10,000 hours. Why go another route?
If you are referring to the spiral bulbs that have a threaded base to go into a std lamp socket, I believe the color temp isn't what you would want for aquarium use. I'm pretty sure it wouldn't work for a reef tank, fish only you may be ok.