The problem with monitors are that there are all sorts of 'experts' giving bad info, and the really amazing animals are not good for beginners (expense, rarity, size, etc.).
For example, as previously mentioned, Kim's (Varanus glauerti) are expensive and difficult to find if you don't know where to look. I would not suggest them as a beginner monitor.
Your best bet would be ackies as they're extemely widespread as CBB individuals. Timors (V. timorensis or V. auffenbergi) are also widely available, but i would say almost all you will find will be WC. Tree monitors are mid sized and wonderful, but can be fragile/expensive. Many of the widely available monitors (niles, waters, and the albigularis/exanthematicus group) are a terrible idea for a first foray into varanids.
There are many people with monitor experience on the board, but I'm just sayin, find what you like and start researching. Also, if you're not interested in Ackies, and the other Odatria, what is it that you're looking for in a monitor?
http://www.mampam.com/index.php?opti...id=0&Itemid=86