As you said, most of them cost between 1K and 2K.
But your S-AFC isn't a standalone... it's a piggyback that modifies the AFM/MAF's voltage in order to change the amount of fuel the engine gets (which is basically a ghetto rig but it works fairly well for mild applications).
Also, 120 mph isn't that fast

Well, it's not that fast on a long, straight stretch of interstate with no cars in front of you... anywhere else (besides a race track) is just idiotic.
I agree, 400 ft lbs of torque is NOT a toy for a kid who just got his head full of a bunch of really bad ideas to play with... that's more dangerous than 400 HP persay, because 400 HP isn't nessicarily all that much unless you're flooring it AND revving it all the way out, but 400 ft lbs of torque can cause a whole lot of trouble with just a little bit of throttle, depending on the conditions.
Also, the new NFS game looks like it might be fun, but the god damn PC demo only comes with keyboard controls! WTF! Who wants to play a racing game with a keyboard for chrissakes?