If you can stand the appearance, second-hand store desklamps (like I use) work great with screw-in curly CFLs which can be had in six-packs of 15W, 6500K, for <$20. And you can vary the distance to substrate or get higher wattage. Put a shallow reflector on a hanging fixture. Lots of ways to get light.
This is my favorite method because it is cheap and easily customizable. 2700k bulbs won't be nearly as good for growing plants, but you could try it. If I were you I would just use the 2700k around the house (way better then incandescent anyways), and buy 6500-6700k (usually labeled as "daylight") for your aquarium.