Cold air intake will be the easiest and cheapest thing.
Is it auto or manual??
........ alot will say go 5spd manual if its auto, it'll give you about the same boost as the extractors+ its funner. If a manual is outa the $$$ range(and you got a auto) , go a shift kit
You could also look at cams, and chips. Hold off on the chip till youve finished filddling around, that way it can be programed to optimise you previous mods
Just my 10c
1st car EA Fairmont Ghia, extractors, exhaust
2nd EF GLi, 'custom' interior, extractors, exhuast
3rd EA Fairmont 5spd, low'd, extractors, exhuast, head
work, 3.45LSD, EL dash, interior+ El ECU
4th EB2 Fairmont, EL dash and interior, BBM, LSD etc etc
5th EB Fairmont Ghia 5L. All leather, lowered, exhaust etc