Seamstress Pricing

I have a black tie Christams Party to go to on Sunday and I bought a new dress for the party.

I bought it to the seamstress and it is $35 for the hem only. Is that a good price?
What's the normal price for a hem on a formal gown like a bridemaid dress?

I can ask my mom, who is a seamstress. I know from experience it depends if there is any detial on the bottom of the dress then it has to be taken up from the top. But no detail, I will ask and let you know.