Powered Compact Fluorescent Grow Lamps (Cfl)

Sonlight compact fluorescent Lamps are high powered compact fluorescent grow lamps (CFL) that can be used as either your primary grow light or as a supplementary light to your main grow light. 

They are available in both blue and red spectrums for vegetative and flowering growth respectively.  They are not as productive as high intensity lights but cheaper to buy and cheaper to run.
No separate ballast is required for these lights, they simply screw into a standard E40 fitting (normal grow light lampholder) and are run directly through a mains plug.