I'll charge friends one of two rates: pro bono publico or full commercial rate. "Mates rates" are an extra 10% - although in practice I've never actually charged a friend, they can't afford my rates. But I'll not let them pay a pittance for my time and go away thinking that was a fair transaction. Same goes for retail - if someone wants to pay wholesale rates then they're free to go to the same source you went to :). Or if you think you're performing a public service then sell at cost. But if you're adding any mark-up then - as others have said - price things properly.