djmuff said:
Yeah, don't use vise grips. They'll chew up the steel and scratch the paint. If you do it yourself, you can use a large adjustable crescent wrench. It's smooth inside so you'll be less likely to damage the paint, and you can adjust it to fit snugly.
Or you can take it to a shop. Most derailleur hanger adjustments are pretty easy. And they have the proper tool. Best thing to do would be to give your local LBS a call and ask.
I'd had the bike shop do some work for me late last summer, replace a fork, etc. so this may have ended up in the equation but they straightened it out for me for n-o-t-h-i-n-g. So, hopefully a bent derailleur hanger is not a big job.
Doing it yourself seems to be a minor engineering feat or at least you need to be certain of the geometry involved. Surely, there might be someone who can do it at a reasonable price. I searched the net for info on this a year ago and it scared me away from doing it myself. Bottomline, I don't think it's anything costly, not be over $35 if that much and in fact, our shop lists service prices online, I thought, well, I'll have to pay for it but they didn't charge anything and they said it was only slightly bent after I was expecting to hear the worst! I don't think it's a big deal with these shops to do such but then again, since they have the tools, sometimes they will charge since it's basically a one time fix.