I'm with Dave on that one. However my F103 is proudly sitting in my trophy case because it's considered not "realistic" enough for some and has been banned from many F1 programs. To be on the safe side, go with the F104 V2 Pro for starters and see how you like it. As Mr Berger will attest, with a few minor upgrade's it's fast right out of the box! You can always do Exotek upgrades once you get to know the car and figure out where your cash would be best spent.
First big investment should be in tires. 70-80% of your tuning troubles will go away with the right set of tires. If you will run the TCS series, the new Tamiya tires that are made by Pit S would be the way to go. Good on carpet and asphalt.