My Character: [Bluff] "It was expensive! The Magus has increased his prices.. It cost around a hundred golden ducats"
Fredoc Hedger: [Success] "Oh? I see. Well, here's the gold back and here is something extra for your troubles."
He indeed gave me back the gold I requested (normal 50 + bluffed 50), but he did not give any "extra" despite saying so.
I did this quest today and made my bluff roll. I got 50 gp + another 50gp for a total of 100gp.