For a small monitor species, I would recommend ackies as well. Yellow ackies will be cheaper, are smaller than red ackies, and are generally more mellow.
Actually all of the dwarf monitors in the US are pretty hardy monitors. The rarity and price of species like v. caudilineatus is why most people do not keep them. You don't find many beginners willing to wait 6-8 months for some to become available then drop $4500 for a trio of v. gilleni even though they probably the best monitors a person could ever own.Certain Dwarf Monitors are quite fragile and wouldn't be a suggested beginner at all, however; these animals are generally in the $600 plus price range.