I'm on a budget and I've spent most of my money repairing my car,and what few mods I do have so far are these:
-Ford Racing 9mm sprak plug wires. (prices are in CDN $) - $57
-Vibrant Performance cone air filter - $35
-Ractive Fireball muffler - (regular price $199,but I got mine free)
-Remove resonator and replace with straight pipe - About $20 with parts and welding,or clamps. Welded preferred.
-Magnaflow high flow catalytic converter - $80
-Window tint - $175
-SVT rims with tires - a steal at $350
-Paint stuff! Whatever a can of paint costs! $6.99 usually.
-Better lights - $28 ea x4 for Silverstars
-SE sideskirts - $60
-Clean,detail,wax,shampoo.
This is only the very beginning stages of my car as well,I've only had it since May.
Best of luck,and you know where we are when you have some questions! These guys have been more than helpful for me. I don't know what'd I'd do without this place. * Group Hug! *