Lets see....
$1400- should see you getting a nice set of DBA Gold Slotted/Cross-Drilled rotors all round, plus some good-ish Ferodo or Bendix pads
$2600- should have you riding on some nicer suspension. This price varies on your needs and brands, but if you don't go overboard that should get you progressive rate lowered springs, good shocks, over-size front a rear sway bar, top-of-strut brace up front and an adjustable panhard rod in the rear.
$500- depending on how extreme you want to go (maybe more if an additional cooler is needed) - should get you a bunch of GenIII parts inc solenoids, valves and springs in your gearbox (If an auto). This will improve your shift speeds and times.
$400- should get you an over-sized throttle body (new) and either a Holden/SS Induction CAI, or intake pipe and a good quality POD filter.
$250- should get you a new reprogrammable memcal. You need this to help tune your car running on Premium Unleaded (or at least I hope it is), your auto's (if you have one) shift points, and your increased airflow. BTW: not exactly sure on price here because I got a special rate, but it should be around there.
$1100- High flow exhaust system, maybe a single mandrel bent mild steel 2.5" system connected to both good headers ie: Pacemaker, and some good cats and kit. I like Lukey, but other brands like MegaFlow are becoming popular.
That about 6k.... I myself have sone this, plus spent a bit more on 18" rims and good rubber, a better feeling sports steering wheel, and a set of SPARCO seats. All in all.. it now handles and drives pretty good.
Next step for me is a CAM, an ECU re-program to make it all work together and a 3.45:1 LSD.
Just my $0.02 worth.