Sounds like you want to buy all the parts separate and build up the car yourself. If that is what you want, you have chose the most expensive way of doing it.

It's much better to get a kit and build that. While some cars share bearing sizes and axles, you can't be sure you get things to fit right unless you buy parts made for the same car. And doing it that way you'll end up paying nearly twice for the car, compared to getting the kit version.