Hi there!
Do NOT purchase from underground reptiles. They are notorious for catching wild animals that are infested with parasites and are sickly and sending them in terrible condition to people such as you. I would
highly recommend that you seek out a reputable breeder instead. Furthermore if you end up with a female (which is likely), she’ll be pregnant and will give birth to tens of babies.
Please read all information on chameleon academy about Jackson’s - especially temperatures and humidity. They are montane animals and need temperature drops to around 60° in order to live a full and healthy life.
I completely understand your desire for a chameleon, and it seems that you’ve done some good research (no Cham kit, 2x2x4, etc…) but keep in mind you shouldn’t use any plastics or fake vines/plants/sticks/rocks in your enclosure. You should get sticks from outside, and live plants from stores like Lowes, Walmart, or Home Depot. Keep in mind you
need to wash the plants with dish soap and water, and will need to repot them into clean, organic, perlite free soil. The first investment for a chameleon is easily $700, and that is the bare minimum. They are tricky animals who have very specific care requirements. They can get sick, and the vet bills are no fun. Also think about what would happen if/when you leave for college? Chances are a cham won’t live that long, but you should plan for it regardless.
I’m just saying to truly do your research completely before making a decision about getting a chameleon, it’s my best piece of advice. If after you read this, and do your research, you still feel like you can do it - awesome! There are other young keepers here on these forums, they may be able to give you some pointers on how they started!
Best of luck