"I am simply asking you a favour," he replied. "That said, if there is a service I can offer for you, I'd be much obliged. But, I ask because this is something that could drastically improve my quality of life. It means no more fearing I'll hurt someone. And while I know you're not my biggest fan, I'm hoping you'll do this because you're good at potions and I'm willing to pay a modest sum. I cannot, however, pay what the going price is for this potion."
"And," he added. "Should you be able to provide this service to me, I have several connections to other people who seek this potion and could also pay a modest but noteworthy sum for it. I am also currently working to raise funding to pay for someone to brew this potion for more disadvantaged persons, so once that money comes through, there'd be a larger client base and more profit for your work."