I have one from Jessops which uses a rechargeable battery which lasts 15min on one charge, Bulb life was 35hrs . Cost about £45. Brilliant for the cost though .The bulb is halogen and very bright
I'm not sure they make them any more
A simple Google search brought
THIS
The Hama on there looks interesting although it uses 2 AA batteries ( for 2 hr) ..you may find it handy even if its hardly likely to light up a tennis court!
Bigger lights cost more and are more intrusive but will get you better video.
Some camcorders have built in lights which are convenient but largely ineffective and just use up battery life
With all, the ability to adjust white balance on the camcorder is very desirable to avoid an unnatural colour cast