Is $1,356 to clean a kitchen drain a fair price?

I am managing a large rehab project for another homeowner who is currently hospitalized. I've generally been permissive with my contractor buddy's decisions, but I'm starting to worry because he's done work without checking first, and some invoices seem high, especially for jobs without significant material costs. This specific kitchen drain cleaning, which didn't sound like a major task, resulted in a $1,356 invoice. I'm trying to determine if this is a fair price, particularly since he isn't a licensed plumber and was already on-site for other agreed-upon work. I want to ensure I don't have to start being less trusting of his on-the-fly decisions.