You will find that most of the breeders of Northerns have wait lists, so they sell out as soon as the litter is born. The ones that are "cheaper" are generally one of the Indo species that are still being exported, either as "farm raised" or wild caught. I'd recommend going over to bluetongueskinks.net and reading through the many threads, care sheets, and species info. A lot of the people over there are breeders as well.