What Chris has said is on the money, you really need to think long and hard what you are going to do, it can cost a lot of money to produce a car even if some of the work is done in house i know
With the Slim4 i have already invested well into four figures and i am over a year into the project, and i have three cars to show for it.
I think you need to decide what chassis / base car / you are going to start with first
