I'm going to check out Donalds links when I get the chance. I've done the home-made builder's light thing; shakey to set up, hot spots, burned furniture... I really do not do enough portrait work to have much of an opinion, but I'm guessing you want something to enhance the existing natural light, rather than the artificial studio-mug-shot thing? Not sure what capabilities your cameras have for metering flash through the lens, (Canon Rules! hehe!). Metering tends to be the biggest problem with flash, but in your price range there should be some sort of flash-meter. Second problem is always previsualization. With flash it is helpful to also use a low wattage continuous modeling light just to see where everything is pointing.