Depends on how bad the gouge is, but you could get some "plastic padding" or "chemical metal" to fill the damaged area, then carefull file it all back flat with a nail file, emery paper etc. and finally spray with a good match sliver/gray paint from Halfords.
p.s. I was going to add that I have tried this with excellent results on my V70 T5 but didn't want to start another "Oh my God he drives a Volvo" thread
With previous cars I have used my local coachworks who do an excellent job on removing scratches and dings for approx £25 a wheel. Have a phone around your local ones.
