Choosing a Video Camera
Getting good, bright lights that can evenly illuminate a green screen is half the battle.  The other half is using a camera that will give you a clean key by not blending together too many pixels in its macroblocks.  Many low-end camcorders use 4:2:0 chroma sampling, which means the border between your key and your subject is going to be at least two pixels wide, and difficult to properly clean up.  Higher-end camcorders user 4:2:2 chroma sampling, and the best use either 4:4:4 or RAW encoding.

You can see for yourself how these different chroma sampling systems affect the edges you are trying to key.  If you are doing your own post-production for fun, and you have the time to futz with fuzzy edges, you can certainly spend time in place of money and get results that make you happy.  But if you are trying to do a live broadcast and you need keys that "just work", then 4:2:2 is probably the minimum color spec that you will want to work with.