Paying a family friend for alterations on a dress

I bought a dress for my fiance's Fire Department dinner. A family friend helped with the alterations. She is only charging me $22. I did go to her to save money, but I think thats to little of a charge. Can someone tell me how much a seamstress would actually charge. I want to give her something in the middle. I was thinking around $40.


Can someone help me?