Blue Tongue Skinks are great lizards, but they aren't really the best "beginner" species. Most of them wind up losing their homes due to their large size and somewhat expensive care needs. Here are some things to consider:
- A blue tongue skink is VERY susceptible to metabolic bone disease. It must have a high quality, high intensity UVB light, and that light needs to be changed every 6 months at LEAST. These lights are a bit pricey, depending on the caliber you purchase anywhere from $10-50 per bulb.
- Ideally in warm months you should (safely) expose them to natural sunlight with supervised outdoor time as much as humanly possible.
- Calcium, Calcium w/D3, and Multivitamin supplements will be required.
- A large enclosure is essential at maturity. These animals get to be large and they are active/wide-ranging in the wild. IMO, anything less than the footprint of a 75g aquarium is totally inappropriate, though you'll see reccomendations for less.
- A basking area of a good 95-100 degrees is necessarry (varies a bit species to species, you need to find out EXACTLY what species you are getting). This means a high wattage heat bulb, and depending on how cool your house is, possibly both a heat bulb and heat mat.
- As omnivores, nutrition is a little more complicated that just tossing some dusted crickets in the pen. They need about 60/40 plant/animal. It is hard to find good info on the type of greens you should feed these guys, but check out greenigsociety.org for the best idea of an appropriate "salad." It NEEDS to be fresh greens to prevent deficiencies. You can also feed squash family vegetables, berries, mangos, etc. as part of the vegetation portion of the diet. The animal portion of the diet should be dominated by invertebrates; too much vertebrate protein (ie. mice) can lead to vitamin excesses and obesity. Crickets, mealworms, earthworms, roaches, etc. should be fed in as great a variety as possible. Relying on a single prey species tends to result in poor nutrition. And remember to always gutload prey and use an appropriate vitamin dusting schedule. Obviously feeding these guys can be pretty expensive.
- Provide as enriched an environment as you can. These are very intelligent, active animals. They like to root under substrate but they also like to climb a little bit; giving them logs and the like presents natural obstacles like they would face in the wild. Novel object/scent/texture stimuli are important forms of enrichment, as is simply bringing you skink out to explore and interact.
I would really suggest looking for a good skink forum for more info (I think it goes without saying to ignore anything a pet store tells you). There are a lot of misconceptions about these guys, and many of them lose their homes or their lives young. Do consider looking into adopting a skink rather than buying, as reptile rescues, shelters, and private individuals often have them available.
Done right, these guys are awesome pets that your son will enjoy for years!