The best book by far, read King and Greens monitor lizard biology, to understand what a monitor is and get ideas what they need. Ask lots of specific questions here. Care shetts suck, they are written mostly as an absolute and they dont specify that individuals are different not differences by species, which matter just as much or less.
Cage size- lots and lots, 4x4x8ft as an adult. give them enough room as an adult to allow their entire body size in each range of temps.
Substrate- dirt, how about lots of field dirt that strained, how about 1.5 to 2 feet deep over the whole cage, as an adult.
Temps- Basking 130f plus (surface temps), ambient warm end 86f (air), ambient cool end (air) at between 68-75f.
Water-fresh drinking water available daily, yet also enough room to soak in that dish by choice, a word of warning if they soak alot then your cage needs serious changes.
Food- Crickets, lobster roaches, superworms, hissing roaches, but as soon as they can eat them stick to mice, chicken peeps, quail, with rodents as the basis, rodents are a perfect food and nutrient source as a basis with no suplementation used on them. Supplement all feeder insects with a good calcium vitamin D3 supplement only.
Vets- Find a a good herp vet, not just a regular vet, check ARAV and herpvets for a listing near you, interview the vet ask alot of well informed questions and gauge by their actions with the animal.
Price ranges- 99.9999999% of all bosc monitors are wild caught, ask for proof if claims of CB or CBB, ask for pics of adults copulating, mother laying eggs, eggs incubating, eggs hatching, hatchlings in that persons cages. preferably with them in some pics backgrounds. Anyone who actually has bred any monitors will be more than happy to offer the proof you require, anyone who gets offended, says get a life, threatens you, cant prove it, because they never have had it happen. They are WC so get a good one but dont spend alot as they are imported and sold to petstores, and dealers for $1 each.
This can get you started, warning monitors are expensive to care for properly, the cost of care (proper care) dwarfs the cost of the animal.