Water Monitors can be a joy to work with if you are an experienced herpist (is that even a word, or did I juast make a new word up,,, very tired).
But by no means if you are still living at home and have just bought a black throat (from my understanding), you should really wait and see how you do with your first little guy. I agree that in ayears time you will have two pretty heavy bodied animals on your itinerary if you buy a water now. Wait it out, but by all means while your waiting hop online and look in some books. You can't get all of your herp experience in books but knowledge goes a long.
Rusty
PS that other member is right on, It is not easy finding an adult monitor a good home. Believe me, I know.