Spending your own money on the animals is great, but it really doesn't change the fact that you're in their house and what you are looking to do is effectively run a business out of it. One that involves animals that, four years to eight years (depending on if you go to college, if you do and live at home, or if you wait until you've graduated to move out) so from now, you're going to probably have to leave behind for long periods of time because it's a rare rental that is okay with a SNAKE BREEDING BUSINESS as opposed to a pet snake or two. Which means they're going to have to be on board with that -as well as the whole driving you around for two more years (how are you getting these baby snakes to customers, or are you keeping them all? How are you getting to the vet? How are you getting supplies) and dealing with the risks factors associated with selling. They're also WHO IS LIABLE if a customer or someone sues you.
This is a big deal and you REALLY have to either have your parents on board or need to wait until you're in your own house. And by that I mean own, not an apartment rental. Even if you find a cool landlord, moving with a snake breeding project is going to be awfully hard, and when you're young your job will change frequently and mobility is important.
I let my 15 year old get a snake. I'd let him get a couple of more. If he tried to start a breeding project in his bedroom I would explain most of the above as best I could and make sure he understood WHY it wasn't happening - but it wouldn't be happening for those reasons. Mostly the liability, and fact that I don't want a breeding project and he's 3 years from moving out with a very low likelyhood of moving out to somewhere all those snakes could go. I? Don't want a ball python breeding project and business. So yeah. No.