I don't ever charge anyone for it because all I have to do is push a button. I've had a few people tip, but I don't actually care. Any reasonable amount to charge is barely worth anything.

Also, similar to what the person above said... thanks to the cross-server duty finder, the opportunities to meet and talk with people are few and far between. I'd rather make my first impression the best I can by not asking for a pittance of gil.