If you can't afford it, I'd suggest you wait until you can. These animals, unfortunately, are not cheap to take care of. Keep in mind you need to replace the uvb twice each year ($50). Those 700 reptiworms will be gone in around one week, not two months (expect $30/week in feeders... shipping included). You need to buy greens every week ($7). You will need to keep calcium and vitamin supplements on hand (say $50/year). Say $150 on his baby enclosure, $500 on top of that to set it up. $500 to buy his adult enclosure... depending on how much you can reuse from the baby enclosure, there will be expenses to set that up...
Not trying to be rude (just trying to help!) but unless your parents are willing to drop a whole lot of money on it, a 13 year old can't afford to buy a beardie. That said, you're lucky your parents are ok with you having your own animal. I had to wait until I moved out- then I had to wait until I could afford to live off campus, and then wait before I could afford a hungry lizard. I know how much it sucks :lol:
If you're open to other reptiles, look into Rhacodactylus geckos- cresteds, gargoyles, chahouas, etc... They're good pets and much cheaper to take care of. All you have to feed them is the Repashy brand Crested Gecko Diet, which, $10 worth will go 6 months.