Thats a fair size dent but it really depends how deep it is and if it involves a swage line. If you're thinking about paintless dent removal its probably too big. new wing cost depends on the car and whether its O/E or pattern part, cost to paint depends on paint, met. or solid, and if it needs to be blended into the bonnet and wing, try visiting your local bodyshop for a quote, its free.
Have a look at the Dent Devils site. Mobile service; they'll come to you. I used them about 2 years ago and results were excellent. Cost was �75 for first dent and less for subsequent.