nothing about performance parts are cost effective. You'll need the same parts (mostly) weather the air is forced from the intake side (supercharger)or forced from the exhaust side (turbo). If I was going to build a car for speed I'd go with a N/A motor and get rid of everything except the ALT. and power steering pump (cuz I'm lazy) Plus there would only be a couple of wires to hook up and you can work on the dang thing your self and they are extremely easy to tune.
I was referring to a V8
N/A would net you if your lucky 180whp after some serious mods so ya its not a v8 lol. Stock gt looking at 140-150whp.
On the turbo subject I would not recommend it to you because your knowledge base on the subject isn't vast.
Imo turbo for you is overkill. You haven't experienced 250whp nvm 350whp. Turbo is if you want 400whp+