I find buying drinks for attractive women is sometimes a good investment.
Suspension and brakes is a good start..read the technical section. We've discussed this to death, and it totally depends on what you can find in your car wrecking yards..
For track days, you'll need to look at using stanza lower arms and getting some Datsun 1600/180B larger type struts/brakes installed. Bigger brakes means bigger wheels, a lot of larger brakes don't fit under 13inch wheels. So 14inch mags or 15 inch mags are needed.
No good things in life are cheap, even bad things in life cost money. Make sure you have the funds before starting, with no machine shop facilities or skills you might be looking at $300-$1000 for a brake upgrade.
Uprated pads..not anymore really. There are more benefits in going larger disks/calipers, which generally means a strut change.
Rear suspension, get a reversed eye/extra leaf combination. Pedders can help you there. Doing it yourself (without adequate experience) is dangerous. Budget $500-$1000 for new suspension.
Welcome to the joys of owning a money pit

Maybe the new TV is a good option.
