Thanks for the genuine replies. 'GavThePlumber' I wasn't asking for another quote, just if the price was generally fair, clue was in the title... Undistilled, I said there was a load of issues I wont bother going into, that's why I wouldn't use him again.
Regardless of whether it seems a 'fair' price for the work done, or not I would say that adding that amount onto the bill at the end is a little underhand and not what you would expect from a family friend. You're right to question this and I would personally ask him for a thorough breakdown of 'extra' costs incurred. Looks like he might have plucked a number from thin air as he thought he could get away with it.