Insurance would depend where you live. You can't buy it yourself because you are not old enough to legally enter into a contract. Your parents can buy the insurance and have you as the primary driver.
To give you some ball park, my son (17) when he had an 07 WRX was $2400 a year. By comparison, my Lotus Elise cost me $1200 a year. We live in the second lowest risk town in our state and I also have a bazillion other policies with the same agent, so we're saving literally $1000 a year because of those things.
Can you afford gas? My son estimated he'd spend $60 a week on gas. He spent $100 a week.
When you need tires, do you have $1000 set aside for tires?
If something happens (an 07 is nearing ancient status and used WRXs are beaten like something that gets really beaten) do you have money to pay for repairs?
Taxes, registration costs, loan payment etc. I'm going to guess $2.5k a month total.