And it was less of a bite than I expected. I have 7 fixtures each with two of those curly fluorescents, and a 4 foot fixture with six T5s so that is 20 bulbs.
It is sort of a guesstimate because of the new apt and the fact that I am still running the AC quite a bit, but I estimate around $25 for the lights.
Definitely worth it, not only because it helps my plants, but also the extra light brightens up the living room, the plants and light make it look bright and cheerful.
I have heard that some people (and probably some inside plants too) have a Seasonal Affective Disorder where they get all sad and droopy due to lack of light. The plants and I, with the huge window and the supplemental lighting, are safe from that happening.