1. The Northern blue tongue's scientific name is Tiliqua scincoides intermedia, not Tiliqua nigrolutea.
2. The animal in the picture is not a Northern, it's a Blotched; even though the scientific name does match the photo.
3. The Blotched is not necessarily a desert species and inhabits lots of different terrain. In fact, southern Australia and Tasmania (which are the only places Blotched are found) has some of the coldest winters in all of Australia. Many advanced keepers suggest keeping Blotched in cooler temperatures than any other species of BTS.
4. Northerns aren't particularly more expensive than Easterns, though Blotched are!