If you chose the Z, i hope you make enough money to insure it.
Insurance isnt cheap if youre younger than 23. The Scooby is less expensive to insure than the Z, but i dont know about the s2k.

I think there are better cars out there besides the Z, S2k, and Scooby.
Based on your choice of cars, it looks like your budget is around 20k.
So i with 20k, i would probably get a G35 coupe, even though its the same as the Z, its just more luxurious.