Heres the thing, technology changes.
I bought my stuff piece by piece because Im also at school and my car is at home. I buy what I can find on sale and save them up to work on when I get home. If you're changing cars, you can make a modular system and MAKE SURE you can return the car to factory when you're done. You have to make something that isnt specific to YOUR car.
With that, if you want to, then you might as well. Just keep in mind that in 4 years, the things that cost $200 now are going to run you $40.