2 new genuine wings for an 80 from the main dealer came in at £804 ie £402 each. I'd start there. Getting a price for genuine is always a good benchmark. You might snag a decent second hand one or find some cheaper pattern parts. With new of course you then need them painting. Best result would be a genuine, used in the same colour. Bingo! What about repair? My 80 wings were toast really, but if it's not too bad a decent local body shop might rescue them for less than a new wing plus paint.