Dude, I am in the same situation. I'm gonna get my mom's Corolla from her when I turn 16, and I was thinking about engine swap/turbo/supercharger/nitrous. And in the end it's just not worth it. Modifying the engine is a big deal, and while it can make you a lot faster, it is costly and there is always a chance something will go wrong. It is best to play it safe, because if your car breaks a week after the engine swap, you will not have any more money to waste on another engine. Just put some cool rims on it and put a good sound system or whatever. If you're really into making it perform better get new suspension, exhaust system, or try to reduce the weight.
You said yourself you are afraid of the "$$ issues", so as far as the engine goes, I'd leave it alone and use the money to save up for a nice next car, whenever you are gonna buy one.