In all honesty do you really want to spend ALL your money on a car? it's just a car. I know when I was your age I was like "o shit I want a really nice car that looks sick and is fast and shit. But i'll just cover a couple thoughts that don't go through most 16 year olds minds. Insurance is outrageous for a newer car, I'm kind of figuring your parents will pay your insurance if they're splitting your car costs but some day you're going to have to pay your own. You are 100x more likely to crash or get a ticket if you have this fast car, and will your parents pay for a 200 dollar speeding ticket especially if you drop most of your bank on the car itself. What is going to happen if something happens to your car? if some asshole keys it or you get a nasty scratch or lightly wreck it, what is going to happen? If you have a real nice car you're going to have to drop major buck to pay for it and you'll be pissed. In highschool no one really cares about what car you drive. Sure you're the shit if you have a nice car, but you often become the prick that baby's his car and doensn't have any fun with it.
personally, my first car was a 1993 ford ranger. it was a piece but I needed something to haul a big mower for my lawn care business. I payed 1500 bucks and it was the best investment ever. 4 years later it still runs well, and while it's ugly and dented it gets me by and the insurance is cheap. It's not fast enough for me to ever think about getting a ticket. Plus, I had extra money to spend post-purchase which was nice I could still go out, and still afford gas and shit.
IMO. The rsx is a great deal. 121k isn't a lot of miles for a honda engine, assuming it's all highway miles. According to kelley blue book value for that car in good condition that's a pretty good price. All honda and acura and toyota are going to be uber-reliable and will last for basically forever and I would definitely recommend any of these makes for you considering your price range. But, personally I would lower the price range and save some money, you'll thank yourself later when it comes time for college unless you plan on selling before college. The guys who suggest you drop major bank are full of shit. But the guys who are suggesting older subaru's are completely in their right mind, they are a great car, get good gas mileage and have awd. So moral of the story is that in my opinion the rsx is probably too much car for a first car. Hope this helps. O and to find the best deals, look in the paper for private sellers and look on craigslist, you'll find the best prices there.