I feel your pain, as I'm anal about parking as well, and could not tolerate seeing dents in the car. Although often I find if you park on your own away from the majority of cars in the supermarket car park, you attract other cars that park around you anyway for some odd reason.
The mobile repairers can do some surprisingly good repairs. A colleague had something similar repaired recently in the office car park and we were all sceptical that it could be repaired without a trip to a bodyshop, but it was fine. It took several hours but the end result was an invisible repair, much to our surprise given the location and metallic paint.
As to recommendations, what I would do is the same as I have done with wheel repair. Go to the main dealer and find out who they use when preparing cars for sale. If they have a guy they use all the time, you can be fairly confident he's good. No guarantees he'll be cheap, but he should be good. I always favour good over cheap myself
