lots can be done for not a lot of money! since i started on my bugeye over 2 years ago, i reckon i've spent less than £1500 on mods, and £600 of that was the alloy wheels/tyres.
mine started like this:
and it currently looks like this: (although normally with gunmetal 18"'s alloys)
The cheapest and best mod i think i've done on mine had to be the twisted STI sideskirts off a blobeye, completely changes how the car looks compared to the grey plastic ones