What I always tell people who ask me what kind of studio lights to buy, is to get monolights. They are strobe lights where the head and the powerpack are all one unit. They are by far the easiest to use and to make lighting adjustments. As people have already stated, Photogenic makes great ones.
The problem with a power pack and separate heads is that some of them are far more difficult to tweak your lighting. If you want to add just a little more of a mainlight or a little less background light etc, they are far harder to adjust the ratios.
I would suggest, to start, one Photogenic powerlight( say 600ws). Then get a piece of fomecore for a reflector. I would also suggest a softbox instead of an umbrella as they control the direction of light better. With this setup there are not many situations that you can't photograph. Used Photogenics on ebay are about $300-$350. So for less than $600 you could have a light, softbox, 2 stands.(one for the reflector) and you are set. You probably will need a flashmeter also and they are available used .