I know what I do for my plants that seems to work well is those cheap clip on work lights you can use for your garage the really cheap tin half bowl reflectors with a Compact Fluorescent light in it. I'm currently using multiple 10.5'' housings with a 120 W CF bulbs use the brightest ones you can find they all have lumen output lists on the bulbs the more lumens the better mine are currently putting out 2,000 a piece... I didnt think this would be enough and was planning on them being temporary but I'm getting excellent growth and coloration in all of my CP's including my vft's which call for way more light than most plants. the big bonus other than them being cheap is the mobility you can clip the lights right over the plant and move it as needed and their very cost efficient as far as your electric bill goes... just an idea for a quick fix

I think there are a variety of adequate options. I was even going with the window sill for the longest time! I now have mine under a grolite.

Mine do fine in west and south bright windows without extra light.