What kind if project car are you building?
If you are planning on making it a project car then you are better off using the Impreza L as your starting platform. The L is much cheaper, it's is lighter, they are easily available in 4 door and if you plan on swapping wrx or especially Sti then some of the RS parts won't be sufficient if you plan on big horsepower gains.
Just something to keep in mind. Good luck on finding a car