Spotted a 15W PL encased in a screw on pendant-like fixture going at $29.00 at Turf City's hardware shop (besides MacDonald).

Says it is specifically designed for plants. From labels on the box, they also show the light spectrum with emphasis on the red and blue range, the amount of lux at various distance up to a metre deep and the angle of incidence too.

Brand name is Megaman and it's German made. A piece is enough for a 1 ft cube IMO.

Actual name found the web :MEGAMAN PLANT REFLECTOR E27 15W