If you are not afraid of wiring up an AC circuit, this constant lighting kit may be a good project for you. All the parts can be obtained from home improvement store. The set built by the author cost him $46.07 including 4 100W equivalent daylight compact fluorescent bulbs (but not the umbrella).
Why do you want constant lighting when you already have strobes or flashes? The nice thing about constant lighting is what-you-see-is-what-you-get, which makes adjustments easy. This is particularly helpful for still life photography when there will be no complaints from subject about a constant bright light making the subject uncomfortable. This will also be a good setup for people who make videos.
Source: Nikonian Forum
Keywords: DIY, Do-it-yourself, Studio Lighting