Lser treatments are very useful for reducing port wine stains. It may not be possible to completely eliminate these. The details should be addressed by the doctor performing the procedure and often depends on the exact type of laser available for treatment. Treatment will likely require multiple sessions and the costs vary from region to region .
Depending on where you live can really determine the actual costs. If you go to a dermatologist in a private office verses a hospital, I have found it to be cheaper. In Atlanta, you would be able to get treatments around $200-$400 a pop. I have a large port wine stain on my face as well, so this is from experience. Look up local dermatologists, call them to see what options they have and get an rough estimate of the costs. The laser treatment does help, but depending on your age, where its located on your face, and how dark it is can vary on the actual results.