Pet stores are notorious for giving out bad information (and no, this doesn't include all pet stores). Many stores will sell you many things that you don't need and in some cases, they'll sell things that are downright dangerous for your dragon. So what do you really need? I'm glad you asked! I'll make you a list.
1. You need a cage suitable for your dragon. While its true that a baby is small enough to fit in a 10 or 20 gallon, the problem is that you can't get a proper temp gradient (hot and cool side) and can easily overheat your dragon. Start with a 40 gallon breeder size cage to make life easy, its what your dragon will need as an adult anyway, for the minimum size.
2. You need lights. You need a uvb light (linear tube is best), a fixture for it, a basking light (halogen bulb or similar) and dome.
3. Your dragon will need a basking log, stone, branch, etc.
4. Food dishes
5. Live foods and greens/vegetables
6. Calcium and multivitamin supplements
8. A temperature gun or something similar to measure temps.
I see many cages where the cage is filled to the brim with stuff. By stuff, I don't mean the dragon's basking logs and branches. I mean cages filled with stuffed animals, doll beds, toys, vines all through the cage, and so forth. I want you to remember that more is not always better.
I have actually seen the effects in a rescue dragon where the adult dragon went for years without being given proper room to ever walk around or even turn around in his cage without bumping into something. The muscles start to atrophy. If your dragon can't even walk without bumping into something and has to constantly climb over "stuff" just to "dragon" properly, you need to look at your setup to make sure its conducive to the health and well-being of your dragon.
This is a compiled list of standard supplies that are recommended to people pretty often. These are some of the best and easiest and most affordable links to use. (I know, myself and Heather Thompson searched lol).
*Note: Click on each underlined word to go directly to the product.
Reptisun T8 10.0 24": $18
Reptisun T5HO 10.0 22" (safe at an 18"-36" distance"): $21
Hood mount: $54
Inside mount: $29
CHE: Single $18
2 pack $16
Basking lights: Your best bet is generally going to be your local dollar store, 65w-70w halogen flood light. I actually pick mine up at Dollar Tree for $1 a piece. You can get them for only a few dollars at Dollar general as well.
Calcium: $12 shipped - Sticky Tongue Farms Miner-All. This brand is low enough in D-3 that it can just be used daily. You can purchase from our approved vendor, Tracy from Phantom Dragons. Her price is $12 shipped for one jar or $22 shipped for two. Message here for purchase: Phantom Dragons
Multivitamin: Rep-Cal Herptivite $17
Probiotic: Bene-Bac $16
Shelving: Walmart Muscle Rack. Can be picked up at the store or shipped to your house. $60