My personal favorites are a Mach 1 Grill Delete (~$40 new) and a Mach 1 Chin Spoiler (~$100 new). Then lower it and get some different wheels (Bullitts, Cobra's, Cobra R's, etc). That should spruce things up a bit. The wheels and tires would be the most expensive so you could save those for last if you're on a budget. At least that's what I would do if I were just going for looks.